Add support for `claims` like `auth_time` #897

Job	Run time
spm-build-test (macos-15, macosx)	2m 19s
spm-build-test (macos-15, iphonesimulator)	3m 32s
pod-lib-lint (macos-15, GoogleSignIn.podspec, --use-static-frameworks)	12m 9s
pod-lib-lint (macos-15, GoogleSignIn.podspec)	7m 26s
pod-lib-lint (macos-15, GoogleSignInSwiftSupport.podspec)	6m 5s
pod-lib-lint (macos-15, GoogleSignInSwiftSupport.podspec, --use-static-frameworks)	6m 36s
	38m 7s

Provide feedback