Add region recording, CLI options, global shortcuts, system notifications and a tray icon for recording

Things to test

You can check the checkbox if something works for you.

CLI background mode options: spectacle -b -R s, spectacle -b -R w, spectacle -b -R r

• Does recording start successfully?
• Do you get a tray icon while recording?
• Does clicking the tray icon finish the recording?
• Do you get an appropriate notification when recording ends?
• Does the video end up where it should when recording finishes?
  • If KIO debug category logging is enabled, you should see something like kf.kio.workers.file: copy() QUrl("file:///tmp/Spectacle.qeAtVT/Screencast_20231103_040057.webm") to QUrl("file:///home/noah/Videos/Screencasts/Screencast_20231103_040057.webm") mode= -1 in the console output.

CLI output options: spectacle -b -R w -o ~/Videos/test/test.webm, spectacle -b -R r -o ~/Videos/test/test.MP4

• Does the stuff from the previous section work?
• Do you get a ~/Videos/test/test.webm file that actually has a WebM container with the VP9 codec?
• Do you get a ~/Videos/test/test.MP4 file that actually has an MP4 container with the H.264 codec?

CLI GUI mode options: spectacle -R s, spectacle -R w, spectacle -R r

• Does recording start successfully?
• Do you get a tray icon while recording?
• Do you get a minimized Spectacle window?
• Does clicking the tray icon finish the recording?
• Does clicking the "Finish recording" button finish the recording?
• Do you get a video player with the finished recording when recording finishes?
• Does the video end up where it should when recording finishes?

Global shortcuts: Meta+Alt+R (RecordScreen), Meta+Ctrl+R (RecordWindow), Meta+Shift+R/Meta+R (RecordRegion)

• Does recording start successfully?
• Do you get a tray icon while recording?
• Does clicking the tray icon finish the recording?
• Does activating the shortcut you started with finish the recording?
• Do you get an appropriate notification when recording ends?
• Does the video end up where it should when recording finishes?

General GUI stuff

• Can you make a selection with the video region selection editor?
• Does pressing Enter or double clicking on the region accept the selection?
• Does pressing Enter with no selection select all screens?
• Does pressing Escape exit Spectacle?
• Can you initiate recording with the 3 recording mode buttons in the viewer UI?
• Does clicking the "Finish recording" button finish the recording?