[fuchsia] Grant CodecFactory capability to GPU process

This allows FuchsiaVideoEncodeAccelerator to use CodecFactory to
create a platform encoder.

Bug: 1373296
Change-Id: I35d5a5b234b6f4e34293e3694e5e55b1c6f62176
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3984321


Commit-Queue: David Song <wintermelons@google.com>
Reviewed-by: Wez <wez@chromium.org>
Reviewed-by: Tom Sepez <tsepez@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1067732}