fix(media) Deprecate startScreenSharing config option for web browsers.

[jallamsetty1]

This is no longer supported as per the w3c spec for getDisplayMedia.

[yyynnn]

what it means?
that we cant start screen sharing dialog programmatically?
latest build breaks that behaviour

[saghul]

Correct. That's a browser limitation, not something we have control over, alas.

[ihcaesar]

Can you revert this change to make at least Chrome/Edge work again?

The discussion under w3c/mediacapture-screen-share-extensions#11 is still open.
Still open also:
Firefox bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1724865
Chrome bug: https://bugs.chromium.org/p/chromium/issues/detail?id=1198918

The Chrome bug may be solved without breaking "top-level transient activation", which is considered as interim option in the open Firefox bug report. The consider option with capability delegation is not implementend in Chrome and Firefox.

So, as interim solution, I'd propose to revert this change or make it user-agent dependant - so we can use this option with Chrome/Edge.