x11/swaysettings: add new port

SwaySettings is a GUI for configuring your Sway desktop.

Features:
- Set and remove auto start apps
- Change default apps
- Change GTK theme (GTK 3 and potentially GTK 2)
- Mouse and trackpad settings
- Keyboard layout settings
- Switch Wallpaper (selected wallpaper will be located at .cache/wallpaper)
- Configure Sway Notification Center

https://github.com/ErikReider/SwaySettings