media: Add P016 raw video format support

P016 is the two-plane 16-bits per channel YUV 4:2:0 video format where
each sample is a two-byte little-endian value.

Plan is to use the P016 for all other format variants like P010 and
P012.

Also Added the missing video pixel format enums to
VideoPixelFormatUnion in histgrams/enums.xml

Bug: 896010
Test: unit_tests --gtest_filter=VideoFrame.*
Change-Id: Ib726f8471cfc2ef7d82302a30de7ea0b0f11337b
Reviewed-on: https://chromium-review.googlesource.com/c/1286934
Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Reviewed-by: Mustafa Emre Acer <meacer@chromium.org>
Commit-Queue: Dale Curtis <dalecurtis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#625050}
14 files changed