libs: dec: h265: support decode for main-444 8bit streams.

Add 444 8bit yuv format AYUV, which can be used to decode
main-444 8bit streams. Currently, this feature is only
supported by media-driver in Icelake.

gstreamer/gstreamer-vaapi#119
4 jobs for master in 1 minute and 39 seconds (queued for 2 seconds)
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  Manifest
passed manifest #43762

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  Build
passed build fedora x86_64 #43771

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canceled build fedora x86_64 #43764

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failed build fedora x86_64 #43763

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