Roster: Fix file drop and take HTTPUpload into consideration

This fixes file drag and drop on the roster window. Additionally,
filetransfer_preference is taken into consideration when trying to
send a file.
3 jobs for fix-roster-file-drop in 2 minutes and 25 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Test
passed #11488
run-appdata

00:00:05

passed #11487
run-tests

00:02:09

 
  Build
passed #11489
run-build

00:00:10