check-python-exists

This is a basic wrapper around the GHA provided actions/setup-python that:

1. avoids the issue with requiring sudo and having /Users/runner/hostedtoolcache on the self hosted runner.
2. Add support for Windows/ARM64 until it is fixed upstream.

• If is-self-hosted: false then this falls back to actions/setup-python at v5.0.0.
• If python-version is provided, that takes precedence over any existing .python-version files
• If running on Windows/arm64, uses a hack hardcoded for 3.11.
• If you need to point to a different .python-version file, pass the path relative to the current working directory to the python-version-file parameter.