compilers: keep MSVC linker flags out of checks

[tianrking]

Compiler.get_compiler_args_for_mode() started including the dynamic linker's always-arguments in 1.11. For MSVC builds, normal targets invoke link.exe separately, but compiler checks link through cl.exe. This placed linker-only options such as /release before /link, where cl.exe rejects them with D8043.

Keep link-mode compiler-check arguments limited to the MSVC compiler's own always-arguments. The regular link step still receives the dynamic linker's always-arguments through the backend.

The regression test uses the real MSVCDynamicLinker and verifies that link-mode compiler arguments do not contain its /release option.

Fixes #16086

Tests:

• python run_unittests.py InternalTests.test_compiler_args_class_visualstudio
• python run_mypy.py mesonbuild/compilers/mixins/visualstudio.py
• git diff --check

[tristan957]

Is there an integration test we can add for this? We have Windows-based CI already

[bonzini]

Touching get_compiler_args_for_mode is scary. The problem is the duplicate flags between super()._sanity_check_compile_args and self._get_basic_compiler_args() - let's just stop calling the former. I'll open a PR for both issues.