Move common codegen code to parent class CodegenCppVisitor

[JCGoran]

Some of the codegen routines are identical for NEURON and coreNEURON, so we may as well put them in the parent class, notably:

• print_function_or_procedure (EDIT: removed for now due to the need for workarounds for v in NEURON codegen)
• print_table_replacement_function (code in Add TABLE statement #1247 does not actually need modifying)
• print_table_check_function
• get_table_statement
• check_if_var_is_array
• print_function_declaration

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 98.77301% with 2 lines in your changes are missing coverage. Please review.

Project coverage is 86.35%. Comparing base (299c249) to head (69a2a1c).

Files	Patch %	Lines
src/codegen/codegen_cpp_visitor.cpp	98.66%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1251      +/-   ##
==========================================
- Coverage   86.36%   86.35%   -0.01%     
==========================================
  Files         176      175       -1     
  Lines       13227    13214      -13     
==========================================
- Hits        11423    11411      -12     
+ Misses       1804     1803       -1     

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[bbpbuildbot]

Logfiles from GitLab pipeline #210557 (:white_check_mark:) have been uploaded here!

Status and direct links:

• ✅ spack_setup
• ✅ build:intel
• ✅ build:nvhpc
• ✅ test:intel
• ✅ test:nvhpc