Promote TEST_ORDERED to first-class interface

[thetic]

Description

TEST_ORDERED and TEST_ORDERED_C_WRAPPER are test-definition macros on par with TEST, IGNORE_TEST, and EXPECT_FAIL_TEST, but they required a separate #include "mutiny/test/Ordered.hpp" rather than being available through the aggregate test.hpp. This change corrects that inconsistency.

• Add #include "mutiny/test/Ordered.hpp" to include/mutiny/test.hpp so the ordered-test macros are available to any file that includes test.hpp.
• Merge docs/ordered-tests.rst into docs/test-macros.rst as a new "Ordered Tests" section. The page-level note ("Include mutiny/test.hpp for all macros on this page") now accurately covers ordered macros too.
• Add TEST_ORDERED_C_WRAPPER to the C Wrapper Macros table and OrderedTest.test.cpp to the Examples table in test-macros.rst.
• Remove the now-redundant standalone ordered-tests.rst page and its toctree entry.

Related Issues

Fixes # (issue number)

Type of Change

• New feature (non-breaking change which adds functionality)
• Bug fix (non-breaking change which fixes an issue)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update

Manual Verification (Optional)

N/A

Checklist

• I have written/updated documentation in docs/ for any user-facing changes.
• My code follows the project's naming conventions (mu::tiny namespace, INCLUDED_MUTINY_ guards, mutiny_ C-prefix).
• For new features, I have considered if a C-interface adapter (.h and .c.cpp) is required for parity.
• I have reviewed the CONTRIBUTING.md file to ensure compliance with architectural guidelines.

[coveralls]

coverage: 98.944%. remained the same — ordered-first-class into main