Add resources unit tests; remove old test hook

[222448082Ashen]

Description

This PR adds dedicated Catch2 coverage for resources path utilities and removes the legacy manual Resources test registration from the old sktest runner.

Summary of changes:

• Added unit_test_resources.cpp with tests for:
• path_to_resources
• path_to_resources(kind) for all resource kinds
• set_resources_path
• path_to_resource
• Added platform separator helpers in the new test file for stable path assertions.
• Added an RAII guard in the new test file to restore the original resources path after each test case.
• Removed old run_resources_tests registration from test_main.cpp.
• Removed old run_resources_tests declaration from test_main.h.

Motivation and context:

• The previous resources test path was a legacy manual print-based check in sktest.
• This change migrates resources verification into automated unit tests so behavior is asserted and regressions are caught by CI/test runs.
• The RAII guard prevents global resource path state leakage across tests.

Dependencies required for this change:

• No new runtime dependencies.
• Uses existing Catch2 unit test setup already present in the project.

Fixes #

Type of change

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

How Has This Been Tested?

Current status:

• Not executed in this shell due local CMake/toolchain mismatch in the current PowerShell environment.

Reproduction steps:

1. Open an environment with the project’s expected build toolchain (MSYS2/MinGW as configured for this repo).
2. From cmake, run: cmake --preset Windows
3. From cmake, run: cmake --build build --target skunit_tests
4. Run the unit tests binary with resources filter, for example: skunit_tests [resources]
5. Optionally run full suite: skunit_tests

Testing Checklist

• Tested with sktest
• Tested with skunit_tests

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have requested a review from ... on the Pull Request