gif_recording: Integration with Projector

Projector does not support GIF recording, and the user should not be
allowed to select the GIF recording type while in a projector-
initiated session.

This CL implements the following:
- Hides the recording type drop down button if less than 2 recording
  types are currently supported (i.e. we don't bother showing the
  drop down menu for a single option).
- Overwrites the recording type to kWebM in projector-initiated
  sessions.
- Restores the pre-projector-session recording type when the session
  ends.

Fixed: b/267234545
Test: Manually, added a unit test.
Change-Id: I63a49d96ac7dc78312adeffd5273a04fb003f52f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4204924
Reviewed-by: Michele Fan <michelefan@chromium.org>
Commit-Queue: Ahmed Fakhry <afakhry@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1099605}