Add YuvSnapshot support

Stream with YCbCr_420_888 format may be treated as different
usage type on different platforms.

Add YuvSnapshot support. Then pipeline handler can decide
the detail pipe to run.

Treat YCbCr_420_888 as STILL for usage GRALLOC_USAGE_PRIVATE_1.

Signed-off-by: Qingwu Zhang <qingwu.zhang@intel.corp-partner.google.com>
Merged-In: Iadc7aad854242a0879f9be14475b96e026828a33
Change-Id: Iadc7aad854242a0879f9be14475b96e026828a33