Move `FirebaseAppCheckInterop` to `interop-ios-for-google-sdks` repo

[andrewheard]

Updated Package.swift to depend on FirebaseAppCheckInterop in interop-ios-for-google-sdks.

TODO:

• Merge https://github.com/google/interop-ios-for-google-sdks/pull/10 into main.
• Update CocoaPods dependencies and stage them.
• Update Package.swift dependency on interop-ios-for-google-sdks to use a version range.
• Remove FirebaseAppCheckInterop sources from firebase-ios-sdk.

#no-changelog

[google-oss-bot]

Coverage Report ¹

Affected Products

• FirebaseFirestore-iOS-FirebaseFirestoreInternal.framework

  Overall coverage changed from 88.20% (0318934) to 88.19% (b9db56f) by -0.01%.

  Filename	Base (0318934)	Merge (b9db56f)	Diff
  grpc_stream.cc	98.02%	99.01%	+0.99%
  leveldb_key.cc	98.82%	98.14%	-0.69%
  leveldb_mutation_queue.cc	92.42%	93.56%	+1.14%
  leveldb_remote_document_cache.cc	96.55%	94.83%	-1.72%
  task.cc	94.78%	96.52%	+1.74%

Test Logs

• Base (0318934): https://github.com/firebase/firebase-ios-sdk/actions/runs/9486556368
• Merge (b9db56f): https://github.com/firebase/firebase-ios-sdk/actions/runs/9502414921

1. https://storage.googleapis.com/firebase-sdk-metric-reports/MMg4lc3Ye2.html

[andrewheard]

We're no longer planning to move FirebaseAppCheckInterop to a new repo; see #13263 for more details.