Camera2: Docs cleanup, especially units and range

- Add entries for units and range into javadoc
- Fix up existing units entries and add new ones
- Fix up range entries to be consistent for enums
- Add range entries where it makes sense
- Minor fix to javadoc gen to allow for code indentation
- Lots of edits for consistency, especially to
  available* entries.

Bug: 16525650

Change-Id: Id09663d897ec98122073e6e13719731ec0de4dad