GitLab

- Add query set with the types of occlusion query, pipeline statistic
  query and timestamp query.
- Add extension of timestamp query.
- Add query APIs:
  createQuerySet on device.
  writeTimestamp on command encoder, render encoder and compute encoder.
  resolveQuerySet on command encoder.
- Now timestamp query is available on D3D12 backend, other backends are
WIP.


Bug: dawn:434
Change-Id: Icfdb17da7f406bfd1d6e903503b103391d9c7d8c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2415572
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Cr-Commit-Position: refs/heads/master@{#809704}