application-window: Bind model only after loading

Instead of binding collection model at the window creation time, wait
until everything has been loaded to improve loading speed.
4 jobs for wip/exalm/spinner in 20 minutes and 47 seconds (queued for 2 seconds)
latest
Status Job ID Name Coverage
  Build
passed #210451
flatpak:app

00:14:07

 
  Test
passed #210452
flatpak:tests

00:05:45

 
  Review
passed #210453
review

00:00:54

manual #210454
allowed to fail manual
stop_review