[CI] Stop Xcode 14, start Xcode 15.3

[paulb777]

• Update repo instructions for XCode 15.2 minimum
• Stop CI Xcode 14
• Start CI for Xcode 15.3
• zip build instructions pending [Infra] Switch zip building over to Xcode 15.2 #12737
• performance unit tests pending Fix Performance unit tests on Xcode 15 #11903
• OCMock workaround for Fix Xcode 15.3 build error on Intel Macs erikdoe/ocmock#537
• Update Client App to minimum iOS version 12
• Update CoreInternal testspec minimum OS versions for addTeardownBlock
• Delete some ancient pods from the Symbol Collision tests that don't build on Arm Macs
• Fix indeterministic CoreInternal test - thanks to @ncooke3 in [CoreInternal] Make test encoder deterministic to avoid Xcode 15 flakiness #12761

TODOs:

• zip building is pending [Infra] Switch zip building over to Xcode 15.2 #12737
• Fix FirebasePerformance unit tests for macos-14 and Xcode 15 - Fix Performance unit tests on Xcode 15 #11903
• Firestore xcodebuild tests moving to macos-14 blocked on Float CocoaPods abseil dep for patches grpc/grpc#36340
• Firestore cmake tests moving to macos-14 cannot move because Python 3.7 is not available - [Firestore CI] cmake tests migration to macos-14 #12769
• Auth unit test frequent flake - [Auth unit test] testUseUserAccessGroup usually flakes when run on macos-14 via SPM #12767
• Functions quickstart uses Material which doesn't build on Xcode 15
• Fix FIAM test failures on macos-14 - [FIAM unit tests] Fix unit test failures running on Xcode 15 on macos-14 #12770

[google-oss-bot]

Coverage Report ¹

Affected Products

• FirebaseAuth-iOS-FirebaseAuth.framework

  Overall coverage changed from 68.47% (a58216a) to 67.89% (7a3d30f) by -0.57%.

  Filename	Base (a58216a)	Merge (7a3d30f)	Diff
  FIRAuth.m	83.68%	82.53%	-1.15%
  FIRAuthKeychainServices.m	59.66%	52.36%	-7.30%
  FIRAuthStoredUserManager.m	52.87%	17.24%	-35.63%

• FirebaseDatabase-iOS-FirebaseDatabase.framework

  Overall coverage changed from 56.97% (a58216a) to 56.91% (7a3d30f) by -0.06%.

  Filename	Base (a58216a)	Merge (7a3d30f)	Diff
  FIRDatabaseReference.m	6.41%	6.41%	-0.00%
  FWebSocketConnection.m	41.74%	37.19%	-4.55%

• FirebaseDynamicLinks-iOS-FirebaseDynamicLinks.framework

  Overall coverage changed from 61.52% (a58216a) to 57.96% (7a3d30f) by -3.56%.

  Filename	Base (a58216a)	Merge (7a3d30f)	Diff
  FIRDLDefaultRetrievalProcessV2.m	14.04%	0.00%	-14.04%
  FIRDLJavaScriptExecutor.m	24.81%	0.00%	-24.81%
  FIRDLRetrievalProcessFactory.m	100.00%	0.00%	-100.00%
  FIRDynamicLinks.m	71.30%	69.70%	-1.60%

• FirebaseFirestore-iOS-FirebaseFirestore.framework

  Overall coverage changed from 40.71% (a58216a) to 40.81% (7a3d30f) by +0.11%.

  Filename	Base (a58216a)	Merge (7a3d30f)	Diff
  DocumentID.swift	86.44%	86.67%	+0.23%

• FirebaseFirestore-iOS-FirebaseFirestoreInternal.framework

  Overall coverage changed from 88.12% (a58216a) to 88.18% (7a3d30f) by +0.06%.

  Filename	Base (a58216a)	Merge (7a3d30f)	Diff
  exception.cc	23.68%	84.21%	+60.53%
  grpc_stream.cc	99.01%	98.02%	-0.99%
  leveldb_key.cc	99.02%	98.43%	-0.59%
  leveldb_remote_document_cache.cc	96.55%	94.83%	-1.72%
  local_serializer.cc	87.78%	88.33%	+0.56%
  write_stream.cc	91.55%	94.37%	+2.82%

• FirebaseInAppMessaging-iOS-FirebaseInAppMessaging.framework

  Overall coverage changed from 44.74% (a58216a) to 44.73% (7a3d30f) by -0.01%.

  Filename	Base (a58216a)	Merge (7a3d30f)	Diff
  FIRIAMDefaultDisplayImpl.m	1.78%	1.78%	-0.00%
  FIRInAppMessaging.m	3.37%	3.37%	-0.00%

• FirebaseMessaging-iOS-FirebaseMessaging.framework

  Overall coverage changed from 60.03% (a58216a) to 60.14% (7a3d30f) by +0.11%.

  Filename	Base (a58216a)	Merge (7a3d30f)	Diff
  FIRMessagingCheckinPreferences.m	93.07%	98.02%	+4.95%
  FIRMessagingExtensionHelper.m	77.92%	78.79%	+0.87%

• FirebaseRemoteConfig-iOS-FirebaseRemoteConfig.framework

  Overall coverage changed from 72.98% (a58216a) to 72.29% (7a3d30f) by -0.69%.

  Filename	Base (a58216a)	Merge (7a3d30f)	Diff
  RCNConfigFetch.m	74.13%	73.52%	-0.61%
  RCNConfigRealtime.m	50.63%	46.62%	-4.01%

Test Logs

• Base (a58216a): https://github.com/firebase/firebase-ios-sdk/actions/runs/8654128126
• Merge (7a3d30f): https://github.com/firebase/firebase-ios-sdk/actions/runs/8664500985

1. https://storage.googleapis.com/firebase-sdk-metric-reports/58lqOmeB4P.html

[google-oss-bot]

	1 Warning
⚠️	Did you forget to add a changelog entry? (Add #no-changelog to the PR description to silence this warning.)

Generated by 🚫 Danger

[paulb777]

Clean CI here except for a frequent flake from the macos-14 swift-build-run in spm.yml:

Failing tests:
-[UseUserAccessGroupTests testUseUserAccessGroup]

[ncooke3]

Nice! And thanks for opening the separate issues for the TODOs!