[6.0] [Sema] Let protocols define getter requirements for @_staticExclusiveOnly types

[Azoy]

This is a cherry pick of #74901

• Explanation: Allows for protocol requirements to declare getters with @_staticExclusiveOnly types.
• Main Branch PR: [Sema] Let protocols define getter requirements for @_staticExclusiveOnly types #74901
• Resolves: rdar://130447812
• Risk: Low because this code path was only exercised for @_staticExclusiveOnly types which is only Atomic and Mutex at the moment. Previously code that was attempting to use these types as getter requirements did not compile and this change fixes this codepath so that those use cases are now allowed.
• Reviewed By: @tshortli @hamishknight
• Testing: Existing test-cases were modified and new tests were added.

[Azoy]

@swift-ci please test