Translate UI text, localize numbers

[steveatinfincia]

Some spots in the code are already using the Qt translation system even though there are no translations added yet, and some are currently localizing number formatting (lost/damaged packet counters).

This issue tracks which parts of the UI have translations enabled.

• [ ] Settings sidebar
• [x] Settings buttons
• [x] App settings tab names
• [ ] App settings row titles
• [x] GroundPi settings tab names
• [ ] GroundPi settings row titles
• [x] Status panel text
• [ ] GPS widget
• [ ] Downlink widget
• [ ] Uplink widget
• [ ] Air status widget
• [ ] Ground status widget
• [ ] Bitrate widget
• [ ] Home distance widget
• [ ] Flight timer widget
• [ ] Flight mode widget
• [ ] Battery widget
• [ ] About panel (license mostly)