Camera: Enhance support for monochrome camera

- Add new Color Filter Array enum.
- Clarify doc for Bayer pattern related metadata.
- Add DngCreator support for monochrome camera raw.

Test: Camera CTS
Test: Capture a monochrome DNG image and inspect with LightRoom
Bug: 70216652
Change-Id: I329f224e3763dd5c777815a3cbb9dd7bd198c038