* fix: delete desktop capturers when they're not needed

Delete desktop capturer objects by resetting the DesktopMediaList
objects that own them after the sources have been collected. Capturers
that are not delegated are already being reset via a patch on
NativeDesktopMediaList. That is not safe for delegated capturers as
thumbnail generation depends on user events. Deleting the
DesktopMediaList operation is safe for all capturers and releases OS
capture resources as soon as possible.

* fix: add a patch to clean up PipeWire resources

Adding a patch to workaround a Chromium issue:
https://bugs.chromium.org/p/chromium/issues/detail?id=1467060

The patch can be removed when the issue is resolved.