Change the media search widget to work with resource queues and
providers. Create providers based on the user's filerepo settings
and aggregate their responses with the media queue. Stop asking
for more results from providers that are depleted.
Also fixes a rather nasty infinite-loop bug where the API returns
only very few images, and the UI keeps asking for more.
Bug: T78161
Bug: T88764
Change-Id: I65aed3446cd1f056476c56e6e04522c70e49e595
This somehow got missed in the conversion to extension registration.
It's being read as an attribute, but also as a Config setting, which
throws ConfigExceptions if not set.
Change-Id: I261398e269ab60a8787877f8a7ace97c50c2be45