Camera2: add option to prevend autofocus cancel if preview stopped

There are camera HALs which cannot handle the autofocus cancel call if the preview
stopped in startPreview(). Add an option for this HAL's to do not cancel autofocus in this cases.

Change-Id: I0767cc7279405d17afc0b00120cb43e5bb309220
Add an option to maintain the focus mode when using touch-to-focus

There's at least one family of camera HALs that gets "confused" when
the focus mode forcefully changes to auto after setting focus /
exposure area options.

Sticking with the current focus mode still results in effective use
of the focus region, so don't force a switch to auto. The default
behavior remains the original, this needs to be explicitly enabled
on affected devices

Change-Id: Icdb1eb628f5ae4432bf03a64b38bbf054ba005a0
Add WRITE_MEDIA_STORAGE permission

This fixes the issue where the images/pics are not
deleted from the android external 'SD Card' as android does not
allow writing to the external 'SD Card' with just the
WRITE_EXTERNAL_STORAGE permission.

Requires : https://gerrit.slimroms.net/#/c/2723

Change-Id: I34377160b8b8677abc3506d8aca72166b4129425