We have a startstreaming/endstreaming events being fired when the ManagedMediaSource require more data, let's add a `streaming` attribute to simplify the use cases.
<rdar://problem/106332050>
Pull request: https://github.com/WebKit/WebKit/pull/11210
Committed 261366@main (7bd9c17a7a5a): <https://commits.webkit.org/261366@main> Reviewed commits have been landed. Closing PR #11210 and removing active labels.