Disable HDR dimming when screen rotates.

- Disable dimming for screenshot layer

This is to fix HDR flicker in picture-in-picture mode. Because the
screenshot layer of rotation is an SDR image containing
tone-mapping HDR content, and this would cause HDR part to be suddenly
dimmed during rotation along with the entire screenshot, even though
DisplayManager maintains different HDR and SDR while white points during
during rotation animation.

Therefore, we add a hidden api to allow to dim a particular layer. This
effectively sets the white point for that layer to be same as the
display brightness. Then the screenshot with this flag can be used a
part of the rotation animation in order to remove flikering effects.

Bug: 224860402
Test: check HDR vidoes when rotation
Change-Id: Ib5c02635928cb9779e6f7968d2ec0ac9e659420b
Merged-In: Ib5c02635928cb9779e6f7968d2ec0ac9e659420b