Camera: Torch strength control API.

This change contains below new public APIs:
1. Change the torch strength level.
2. Get the torch brightness level.
3. Callback when torch strength level is changed.

Bug: 200174275

Test: atest -c cts/tests/camera on aosp_cf_x86_64_phone-userdebug
Change-Id: I8b2d3a7dd9114986d3171832744a3dd6db092a48
3 files changed