Add unit tests for AMR claim #915

Job	Run time
spm-build-test (macos-15, macosx)	1m 47s
spm-build-test (macos-15, iphonesimulator)	4m 55s
pod-lib-lint (macos-15, GoogleSignInSwiftSupport.podspec)	13m 47s
pod-lib-lint (macos-15, GoogleSignInSwiftSupport.podspec, --use-static-frameworks)	12m 21s
pod-lib-lint (macos-15, GoogleSignIn.podspec, --use-static-frameworks)	12m 25s
pod-lib-lint (macos-15, GoogleSignIn.podspec)	9m 29s
	54m 44s

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