[gpu] Add GpuMemoryBufferHandle to ExportedSharedImage

Add an optional GpuMemoryBufferHandle to ExportedSharedImage in
order to be passed over mojo. This change adds optional GMBHandle to
ExportedSharedImage and updates callers of ExportedSharedImage.

It also updates Export, ImportUnowned and ClientSharedImage ctors
based on the ExportedSharedImage with GMBHandle.

NOTE: Creation of GpuMemoryBuffers requires BufferUsage which will
be added in follow-up. We'd also like to add a bool in follow-ups
that specifies if Export() should export a cloned handle or
not based on clients that require it.

Inspired from https://chromium-review.googlesource.com/c/chromium/src/+/5737963
by Vikas.

Bug: 391788839
Change-Id: Iee51901b98fb73a5898ad01cb45412956102d8a0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6207476
Reviewed-by: vikas soni <vikassoni@chromium.org>
Reviewed-by: Vasiliy Telezhnikov <vasilyt@chromium.org>
Reviewed-by: Dominic Farolino <dom@chromium.org>
Commit-Queue: Saifuddin Hitawala <hitawala@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1420769}