Add new hdr plus flash setting.

This setting will be used by GcamModule to manage their
torch mode.  It should be different from the Camera 1 api
flash mode setting, because they are semantically different.

GcamModule needs to set enableHdrPlusFlash in the BottomBarSpec
to enable this feature.

Also normalize names, HDRPLUS/hdrplus -> HDR_PLUS/hdr_plus,
for consistency, to reflect the clear majority usage.

Depends on:
* GcamModule ag/465936

Bug: 13076855
Change-Id: I6fe5ab8b1c7b9fa1acd1181445748c0257d21ea4
8 files changed