This gets rid of a flicker where it shows all the results briefly

We create a new one every time because Gtk has some weird behaviour regarding the width of the combo box.
When we add items that are large, the combobox resizes to fit the content.
However, when we add items again that are all smaller (e.g. for a new server), the combo box does not shrink back.
The only proper way seems to be to recreate the combobox every time

Normal disconnect is deprecated. The crash fixed in
eduvpn@0613a76
should not be a problem any more as we're ensuring the correct thread is used already

When the user disconnects in the app but then reconnects with
networkmanager a broken connection occurs. This is because a connect
can only happen with a fresh config, this is only ensured by the
app. We thus hide the connection from network manager after a disconnect.

- Set disconnecting first due to otherwise having an invalid transition
- Do not cleanup the connection, only do that when we actually click on the toggle
- Run in a background thread to ensure the UI thread won't block

- Remove a server
- Change profile
- Cancel the popup

The backend implementations need to be done still

- We should automatically reconnect
- The self prefix was incorrect

- Just running action and then main_loop run gives a race condition
- If action finishes quickly, or is not threaded then main_loop.run will never quit because quit() is called before the run() method
- Use GLib.idle_add such that the action is scheduled to run on the main loop

- Done with absolufy-imports https://github.com/MarcoGorelli/absolufy-imports

Also checked and modified by hand. Additionally I ran mypy on the results

- Reorder to alphabetic order (list was not in the right place)
- Lower case first word of help

- The error dialog should show two buttons if the error can be ignored, otherwise just 1 that will quit the client
- Call the error dialog on deregister exception with the right thread
- The window should be presented and then initialized, otherwise a
quit on an error dialog will not close the client

- This also fixes a GTK (?) bug where the padding causes the whole
search to crash