mainWindow: set a default title for zero sounds recorded

Previously we set the window's title to "" when there were no
sounds recorded. On some desktops, this caused an issue where
sound recorder was labeled "Untitled Window".

Now Sound Recorder sets the title to "No Recorded Sounds".

Fixes #34
3 jobs from wip/christopherdavis/set-window-title in 1 minute and 11 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
passed #202385
flatpak

00:00:27

 
  Deploy
passed #202386
review

00:00:24

passed #202387
allowed to fail manual
stop_review

00:00:19