feat: add GetMeasurementProtocolSecret, `ListMeasurementProtocolSec…

…rets`, `CreateMeasurementProtocolSecret`, `DeleteMeasurementProtocolSecret`, `UpdateMeasurementProtocolSecret` methods to the API

feat: add `GetGoogleSignalsSettings`, `UpdateGoogleSignalsSettings` methods to the API
feat: add `CreateConversionEvent`, `GetConversionEvent`, `DeleteConversionEvent`, `ListConversionEvents` methods to the API
feat: add `CreateCustomDimension`, `GetCustomDimension`, `UpdateCustomDimension`, `ListCustomDimensions`, `ArchiveCustomDimension` methods to the API
feat: add `CreateCustomMetric`, `GetCustomMetric`, `UpdateCustomMetric`, `ListCustomMetrics`, `ArchiveCustomMetric` methods to the API
feat: add `GoogleSignalsState`, `GoogleSignalsConsent` types
feat: add `GoogleSignalsSettings`  type
feat: add `MeasurementProtocolSecret` type
feat: add `ConversionEvent` type
feat: add `CustomDimension` type
feat: add `CustomMetric` type
feat: extend `ChangeHistoryResourceType` enum to support `GOOGLE_SIGNALS_SETTINGS`, `CONVERSION_EVENT`, `MEASUREMENT_PROTOCOL_SECRET`, `CUSTOM_DIMENSION`, `CUSTOM_METRIC` values
fix: label `email_address` field of `UserLink` type as immutable
fix: label `name` field of `UserLink` type as output only

PiperOrigin-RevId: 375776214