Create Profile and Profile management

[cedlemo]

• add a name
• save most settings
  • color
  • fonts
  • Gio::Settings
  • which backend ?

[cedlemo]

Profiles should be stored via GSettings in a list of settings:

• https://github.com/GNOME/gnome-terminal/blob/master/src/org.gnome.Terminal.gschema.xml#L97
• https://github.com/gnunn1/tilix/blob/master/data/gsettings/com.gexperts.Tilix.gschema.xml#L517