[pitivi] After an async discovery is done, emit a signal with missing codecs to install
Submitted by Jeff Fortin Tam @nekohayo
Link to original bug (#686181)
Description
GES will need to do the clip discovery for us, maintain the list of clips in a given project's library, but it should also tell us what codecs are missing so we can trigger the gstreamer codec installation dialog (if that thing still exists).
Version: 1.x