Camera: Fix up metadata generation, including HIDL gen

- Merge NDK and SDK metadata definitions back together
  - Add special linkify handling for SDK/NDK alternate names
  - Add ndk/sdk specific notes/details tags
  - Use new tags/link format to merge ndk_metadata_properties docs
    into metadata_properties
- Rename metadata_properties to metadata_definitions for clarity
- Move SDK reference images to /reference/images/camera2/...
- Add HIDL metadata HAL field to entries, defaulting to 3.2
- Output HAL version into docs.html and camera_metadata_tags.h

Outputting new HIDL module defintions for new metadata versions will
be in a later CL.

Bug: 29102963
Bug: 33262893
Test: Builds, manual inspection of resulting generated files
Change-Id: Ib61111ebf3a068fe62b7a3305b6ab462619c39bb
17 files changed