feat: add the `counting_method` field to the `ConversionEvent` type
feat: add the `ConversionCountingMethod` enum
feat: add the `ITEM` option to the `DimensionScope` enum
feat: make the field `default_uri` of `WebStreamData` mutable
fix!: add the missing `REQUIRED` annotation to the `update_mask` field of `UpdateMeasurementProtocolSecretRequest`
PiperOrigin-RevId: 559470845