This PR removes more FileManager code that is duplicated from swift-foundation. It removes a handful of functions that are no longer necessary, removes the private ._userImmutable file attribute since it is the same as the API .immutable attribute, and updates the private file attribute fetching/setting functions to call down to the public API functions to handle all API attributes instead of duplicating code for the API attributes.
This PR removes more FileManager code that is duplicated from swift-foundation. It removes a handful of functions that are no longer necessary, removes the private
._userImmutablefile attribute since it is the same as the API.immutableattribute, and updates the private file attribute fetching/setting functions to call down to the public API functions to handle all API attributes instead of duplicating code for the API attributes.All tests pass locally on linux with this change