Switch the get_platform_fs_structure, get_firmware_fs_structure,
get_platforms_directory and get_roms_fs_structure tests from mocking
os.path.exists to mocking glob.glob, matching the new STRUCTURE_PATH_B
detection logic. Rename the existing high_priority/normal_structure
variants to structure_a/structure_b for clarity, and fix
test_platform_specific_behavior so its monkeypatch wraps the calls
instead of being applied after them.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
