Add getActiveIntrinsicZoomRatio to ZoomState

Active intrinsic zoom ratio is changed dynamically when a logical
multi-camera switches its underlying physical camera during zoom.

- Add default getActiveIntrinsicZoomRatio() to ZoomState marked with
  @RestrictTo(LIBRARY_GROUP) and TODO b/317468002 for next alpha.
- Support activeIntrinsicZoomRatio in ImmutableZoomState and ZoomValue.
- Monitor LOGICAL_MULTI_CAMERA_ACTIVE_PHYSICAL_ID in ZoomControl on
  API 29+ to update the active intrinsic zoom ratio in ZoomState.
- Add unit tests for ImmutableZoomState, ZoomValue, and ZoomControl.

Bug: 317468002
Test: ./gradlew camera:camera-core:build,
      ./gradlew camera:camera-camera2:build
Change-Id: I7d31a2166581be01ce6a17e55d2b3caf7a439a27