swift

3b77e2e6 - AST: Introduce experimental support for an `anyAppleOS` availability domain.

AST: Introduce experimental support for an `anyAppleOS` availability domain. `anyAppleOS` represents a meta-platform for availability checks that can be used to check availability across all of Apple's operating systems. It supports versions 26.0 and up since version 26.0 is the first OS version number that is aligned accross macOS, iOS, watchOS, tvOS, and visionOS. Apple platform-specific availability specification take precedence over `anyAppleOS` availability specifications when specified simultaneously. Resolves rdar://153834380.