Add support for Intel and NAG compilers

[yanjen]

Hello and happy holiday.

This PR makes FortUTF works for Intel (ifort) and NAG (nagfor) compilers.
What have to be changed:

1. KIND variables has to be assigned by selected_<type>_kind to work for NAG compiler. Reference here
2. Some widths for edit descriptors cannot be neglected or be 0 for NAG compiler.
3. CALL EXIT is a GNU specific function, change to STOP

This PR also adds a workflow for Intel compiler.
The NAG compiler is not opensource, but I have checked the validation locally.
Here is the compile message for NAG compiler.

Scanning dependencies of target FortUTF
[  2%] Building Fortran object CMakeFiles/FortUTF.dir/src/utilities.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
[NAG Fortran Compiler normal termination]
[  4%] Building Fortran object CMakeFiles/FortUTF.dir/src/suite.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
[NAG Fortran Compiler normal termination]
[  6%] Building Fortran object CMakeFiles/FortUTF.dir/src/assertions.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
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[  9%] Building Fortran object CMakeFiles/FortUTF.dir/src/specials.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
[NAG Fortran Compiler normal termination]
[ 11%] Building Fortran object CMakeFiles/FortUTF.dir/src/string_check.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
[NAG Fortran Compiler normal termination]
[ 13%] Building Fortran object CMakeFiles/FortUTF.dir/src/test_suite.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
[NAG Fortran Compiler normal termination]
[ 16%] Linking Fortran static library libFortUTF.a
[ 16%] Built target FortUTF
Scanning dependencies of target FortUTF_Tests
[ 18%] Building Fortran object CMakeFiles/FortUTF_Tests.dir/tests/test_assertions/test_aequal_int.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
[NAG Fortran Compiler normal termination]
[ 20%] Building Fortran object CMakeFiles/FortUTF_Tests.dir/tests/test_assertions/test_aequal_real.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
[NAG Fortran Compiler normal termination]
[ 23%] Building Fortran object CMakeFiles/FortUTF_Tests.dir/tests/test_assertions/test_assert_bool.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
[NAG Fortran Compiler normal termination]
[ 25%] Building Fortran object CMakeFiles/FortUTF_Tests.dir/tests/test_assertions/test_equal_char.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
[NAG Fortran Compiler normal termination]
[ 27%] Building Fortran object CMakeFiles/FortUTF_Tests.dir/tests/test_assertions/test_equal_complex.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
[NAG Fortran Compiler normal termination]
[ 30%] Building Fortran object CMakeFiles/FortUTF_Tests.dir/tests/test_assertions/test_equal_int.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
[NAG Fortran Compiler normal termination]
[ 32%] Building Fortran object CMakeFiles/FortUTF_Tests.dir/tests/test_assertions/test_equal_logical.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
[NAG Fortran Compiler normal termination]
[ 34%] Building Fortran object CMakeFiles/FortUTF_Tests.dir/tests/test_assertions/test_equal_real.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
[NAG Fortran Compiler normal termination]
[ 37%] Building Fortran object CMakeFiles/FortUTF_Tests.dir/tests/test_assertions/test_gt_int.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
[NAG Fortran Compiler normal termination]
[ 39%] Building Fortran object CMakeFiles/FortUTF_Tests.dir/tests/test_assertions/test_gt_real.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
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[ 41%] Building Fortran object CMakeFiles/FortUTF_Tests.dir/tests/test_assertions/test_gteq_int.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
[NAG Fortran Compiler normal termination]
[ 44%] Building Fortran object CMakeFiles/FortUTF_Tests.dir/tests/test_assertions/test_gteq_real.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
[NAG Fortran Compiler normal termination]
[ 46%] Building Fortran object CMakeFiles/FortUTF_Tests.dir/tests/test_assertions/test_ischar.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
[NAG Fortran Compiler normal termination]
[ 48%] Building Fortran object CMakeFiles/FortUTF_Tests.dir/tests/test_assertions/test_iscomplex.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
[NAG Fortran Compiler normal termination]
[ 51%] Building Fortran object CMakeFiles/FortUTF_Tests.dir/tests/test_assertions/test_isint.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
[NAG Fortran Compiler normal termination]
[ 53%] Building Fortran object CMakeFiles/FortUTF_Tests.dir/tests/test_assertions/test_isreal.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
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[ 55%] Building Fortran object CMakeFiles/FortUTF_Tests.dir/tests/test_assertions/test_lt_int.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
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[ 58%] Building Fortran object CMakeFiles/FortUTF_Tests.dir/tests/test_assertions/test_lt_real.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
[NAG Fortran Compiler normal termination]
[ 60%] Building Fortran object CMakeFiles/FortUTF_Tests.dir/tests/test_assertions/test_lteq_int.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
[NAG Fortran Compiler normal termination]
[ 62%] Building Fortran object CMakeFiles/FortUTF_Tests.dir/tests/test_assertions/test_lteq_real.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
[NAG Fortran Compiler normal termination]
[ 65%] Building Fortran object CMakeFiles/FortUTF_Tests.dir/tests/test_assertions/test_nequal_char.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
[NAG Fortran Compiler normal termination]
[ 67%] Building Fortran object CMakeFiles/FortUTF_Tests.dir/tests/test_assertions/test_nequal_int.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
[NAG Fortran Compiler normal termination]
[ 69%] Building Fortran object CMakeFiles/FortUTF_Tests.dir/tests/test_assertions/test_nequal_logical.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
[NAG Fortran Compiler normal termination]
[ 72%] Building Fortran object CMakeFiles/FortUTF_Tests.dir/tests/test_assertions/test_nequal_real.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
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[ 74%] Building Fortran object CMakeFiles/FortUTF_Tests.dir/tests/test_assertions/test_val_in_arr.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
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[ 76%] Building Fortran object CMakeFiles/FortUTF_Tests.dir/tests/test_specials/test_specials.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
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[ 79%] Building Fortran object CMakeFiles/FortUTF_Tests.dir/tests/test_string_check/test_string_compare.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
[NAG Fortran Compiler normal termination]
[ 81%] Building Fortran object CMakeFiles/FortUTF_Tests.dir/tests/test_suite/test_failing.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
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[ 83%] Building Fortran object CMakeFiles/FortUTF_Tests.dir/tests/test_utilities.f90/test_utilities.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
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[ 86%] Building Fortran object CMakeFiles/FortUTF_Tests.dir/tests/test_suite/unfinished_test_check.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
[NAG Fortran Compiler normal termination]
[ 88%] Building Fortran object CMakeFiles/FortUTF_Tests.dir/run_tests.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
[NAG Fortran Compiler normal termination]
[ 90%] Linking Fortran executable FortUTF_Tests
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
[ 90%] Built target FortUTF_Tests
Scanning dependencies of target DEMO_PROJ_Tests
[ 93%] Building Fortran object examples/demo_project/CMakeFiles/DEMO_PROJ_Tests.dir/src/demo_functions.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
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[ 95%] Building Fortran object examples/demo_project/CMakeFiles/DEMO_PROJ_Tests.dir/tests/test_functions.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
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[ 97%] Building Fortran object examples/demo_project/CMakeFiles/DEMO_PROJ_Tests.dir/run_tests.f90.o
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
[NAG Fortran Compiler normal termination]
[100%] Linking Fortran executable DEMO_PROJ_Tests
NAG Fortran Compiler Release 7.1(Hanzomon) Build 7114
[100%] Built target DEMO_PROJ_Tests

This PR also fixes:

1. CHAR length error for logging in specials and test_failing
2. missing assertions in test_isint

[artemis-beta]

@yanjen this is fantastic! Thanks for this, and you even included some CI I am very grateful for that!