feat: stricter selector parsing, refactor to platforms module (#2291)

* feat: stricter selector parsing, refactor to `platforms` module

- Use a different method to build nothing
- Make the check aware of enable groups

* optimise unit tests - a specific platform module API for all configs

Unit test time: 26.2s -> 13.1s

* Remove unnecessary get_platform_module function

unit_test/get_platform_test.py

@@ -7,7 +7,7 @@ import setuptools._distutils.util
 
 from cibuildwheel.ci import CIProvider, detect_ci_provider
 from cibuildwheel.errors import FatalError
-from cibuildwheel.windows import PythonConfiguration, setup_setuptools_cross_compile
+from cibuildwheel.platforms.windows import PythonConfiguration, setup_setuptools_cross_compile
 
 # monkeypatching os.name is too flaky. E.g. It works on my machine, but fails in pipeline
 if not sys.platform.startswith("win"):