Add `usageMetadata` to `GenerateContentResponse` in Vertex AI #9175

Job	Run time
Check changed files	0s
pod-lib-lint-abtesting (iOS)	7m 29s
pod-lib-lint-auth (iOS)	12m 28s
pod-lib-lint-database (iOS)	10m 51s
pod-lib-lint-dynamiclinks (iOS)	9m 56s
pod-lib-lint-firestore (iOS)	29m 39s
pod-lib-lint-functions (iOS)	4m 2s
pod-lib-lint-inappmessaging (iOS)	5m 39s
pod-lib-lint-messaging (iOS)	6m 4s
pod-lib-lint-performance (iOS)	12m 19s
pod-lib-lint-remoteconfig (iOS)	12m 54s
pod-lib-lint-storage (iOS)	10m 32s
create_report	3m 2s
	2h 4m 55s

Provide feedback