Add track selection menu items to media controls

The audio and video track menus are each only visible when there are
more than 1 of the respective types of tracks to switch between. As a
result, this UX is gated behind the
--enable-experimental-web-platform-features flag, which enabls the
exposure of multiple tracks.

DISABLE_SPELLCHECKER
BYPASS_LARGE_CHANGE_WARNING

Binary-Size: The binary size is mostly due to added AX-strings, rather than code. There doesn't seem to be a way to get under the 17kb added without removing the accessibility strings.
Bug: 381024736
Change-Id: I17a17c46a74afdf9f348f3b5cf893f05c2488f8c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6176702
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Ted (Chromium) Meyer <tmathmeyer@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1423248}