media/gpu/vaapi: Use IDMap for allocated VASurfaces

This Cl adds the change to use IDMap for VaapiImagepProccessorBackend's
|allocated_va_surfaces_| which holds the VASurfaces created from and
associated with a |frame|.

Bug: 339518553
Test: video_encode_accelerator_tests, image_processor_tests with forced
VA-API backend

Change-Id: If96363eed95e28d8ccef8f2e7eee6cc8dcc678ea
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5536158


Reviewed-by: Miguel Casas-Sanchez <mcasas@chromium.org>
Commit-Queue: Hang Nguyen <hnt@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1300867}