Settings: Add HeadsUp setting.

Change-Id: Ib7a59145843bedb16aacc87bf6d3c6da143e8d3e
Settings: remove 'Brightness adjustment' from auto brightness dialog

Change-Id: I4cb4a21012fbc0d257a9beff356004bd34f32c9f
Signed-off-by: Roman Birg <roman@cyngn.com>
cherry pick of these two commits:

Settings: Do not disable "Brightness control" setting

It's really annoying to have to back out of this screen when disabling
auto brightness and go back in just to enable this setting.

Change-Id: Iafc217bbad52ac9e3899fb73082e1cf8d825579a
Signed-off-by: Roman Birg <roman@cyngn.com>

Settings: remove auto_brightness_adjustment_title string

The controls which used this string were removed.

Change-Id: Ia1b2aa93f2beea27c17546e293b9aa7c2aa62931
Signed-off-by: Roman Birg <roman@cyngn.com>