[FR]: Move FirebaseAppCheckInterop to interop-ios-for-google-sdks repo

[andrewheard]

Description

To allow FirebaseAppCheckInterop to be used as a dependency in other Google SDKs outside the firebase-ios-sdk repo it would need to be added as a library product in Swift Package Manager. However, we should not add it to Package.swift in this repo since it's not intended for use by 3P developers. We should:

1. Move https://github.com/firebase/firebase-ios-sdk/tree/main/FirebaseAppCheck/Interop to https://github.com/google/interop-ios-for-google-sdks.
2. Add a FirebaseAppCheckInterop product to https://github.com/google/interop-ios-for-google-sdks/blob/main/Package.swift.
3. Update the lower range of

   firebase-ios-sdk/Package.swift

   Lines 190 to 193 in 02d963c

   	.package(
   	url: "https://github.com/google/interop-ios-for-google-sdks.git",
   	"100.0.0" ..< "101.0.0"
   	),

   to the minimum version of interop-ios-for-google-sdks containing FirebaseAppCheckInterop.

API Proposal

No response

Firebase Product(s)

App Check