[App Check] Fix App Attest and DeviceCheck API availability

[andrewheard]

• Updated the FIR_DEVICE_CHECK_PROVIDER_AVAILABILITY and FIR_APP_ATTEST_PROVIDER_AVAILABILITY API availability macros to reflect the set of supported platforms for DeviceCheck (iOS 11+, macOS 10.15+, macCatalyst 13+, tvOS 11+, watchOS 9+) and App Attest (iOS 14+, macOS 11.3+, macCatalyst 14.5+, tvOS 15+, watchOS 9+).
  • Removed the extraneous check for the watchOS 9 SDK now that Xcode 14 is the minimum supported by Firebase.
• Removed the #if TARGET_OS_IOS compiler directive in AppCheckAPITests.swift since TARGET_OS_IOS is only available in Objective-C and was always false.

#no-changelog

[ncooke3]

Nice cleanup!

[ncooke3]

Xcode 13 made that macro an eyesore so it's really great that it's readable again!

[paulb777]

Why is visionOS never mentioned?

[andrewheard]

Why is visionOS never mentioned?

@paulb777 TARGET_OS_IOS is true when compiling for visionOS so we can omit a TARGET_OS_VISION check (but I could add || TARGET_OS_VISION for clarity -- just let me know).

DeviceCheck and App Attest are both supported on visionOS 1.0+ Beta and API_AVAILABLE(ios(11.0), macos(10.15), macCatalyst(13.0), tvos(11.0), watchos(9.0)) in ObjC is equivalent to @available(iOS 11, macOS 10.15, macCatalyst 13, tvOS 11, watchOS 9, *) in Swift. visionOS 1 falls through the unspecified platforms (*) so the API is available there.

[paulb777]

Thanks. I'm good to leave it as is.