drm_hwcomposer: add importer using IMapper metadata

- Add custom drm hwcomposer metadata types

Add a custom aidl interface that implements the plane fds metadata type
for drm_hwcomposer. Also adds new platformgrallocmetadatatypes[.h|.cpp]
files that contains the encode/decode functions for the new plane fds
metadata type. These files can be shared between the
drm_hwcomposer and Gralloc implementations providing support for the new

- Create generic importer for Gralloc 4 API

Create class VendorGraphicBufferMapper which is intended to augment
GraphicBufferMapper by adding support for getting vendor plane fd
vendor metadata.
This is required because GraphicBufferMapper does not provide access
to vendor metadata types and it is not possible to inherit from the
Singleton derived GraphicBufferMapper.
Add alternative to GraphicBufferMapper's importBuffer in
VendorGraphicBufferMapper that imports without validating the buffer

- Use VendorMapper importbuffer over GraphicBufferMapper

Avoid using GraphicBufferMapper just to duplicate the buffer
handle as this will re-validate the properties received from IMapper
using IMapper which is unnecessary and requires the pixel stride, which
cannot be obtained via standard IMapper metadata. Instead, use the
VendorGraphicBufferMapper to do this.

Tested locally on Hikey960 for boot to home screen on Android 11.

Signed-off-by: Dennis Tsiang <dennis.tsiang@arm.com>
Signed-off-by: Ben Davis <ben.davis@arm.com>
Signed-off-by; Paul Howgego <paul.howgego@arm.com>
Signed-off-by: Rosen Zhelev <rosen.zhelev@arm.com>
Signed-off-by: Matteo Franchin <matteo.franchin@arm.com>
Change-Id: I673e40672473f6e8ca054a9b6fa3de26245f433d
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