Bug 2028060 added attributes mimeType, rtpTimestamp and audioLevel to RTCEncodedFrameMetadata. This is a followup to also add receiveTime.

Because of receive timestamp rounding to milliseconds in libwebrtc, they can appear up to half a millisecond into the future, breaking tests. Upstream change https://issues.webrtc.org/issues/42223979 handles that. It's technically orthogonal as the API surface doesn't change, but I think it would be a bad idea to land the webidl change prior to the upstream fix.

This mainly removes TIMEOUT expectations, as prefs disable mDNS in CI.

Also fix some comments, as the DomRealtime clock referred to the wrong epoch.

Upstream commit: https://webrtc.googlesource.com/src/+/273009d2fa8fe3027d4c9a31e8944e2e1e3e8d4e
Move EncodedFrame's receive time to Timestamp

   Bug: webrtc:42223979
   Change-Id: I58db2fbd8ce42bbbb3725b37047f91f4a113b81d
   Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/465242
   Commit-Queue: Andreas Pehrson <apehrson@mozilla.com>
   Reviewed-by: Danil Chapovalov <danilchap@webrtc.org>
   Reviewed-by: Erik Språng <sprang@webrtc.org>
   Cr-Commit-Position: refs/heads/main@{#47526}

https://hg.mozilla.org/mozilla-central/rev/125c53ffd916
https://hg.mozilla.org/mozilla-central/rev/5295cbed89a8
https://hg.mozilla.org/mozilla-central/rev/87983c952548
https://hg.mozilla.org/mozilla-central/rev/912f08f3f04a
https://hg.mozilla.org/mozilla-central/rev/46feaf58fe14

FF152 MDN docs work for this can be tracked in https://github.com/mdn/content/issues/44161