Do `quit()` if the system requested the app to close.

This fixes the issue where a system logout was blocked by bitmask since
we were interpreting the closeEvent as if the user clicked on the 'X'
button.
Closes #5870.
Merge remote-tracking branch 'refs/remotes/ivan/bug/5870_bitmask-prevent-system-logout-on-linux' into develop
Reduce services stop timeout.
Handle the system's quit correctly.

Use a simple sleep to wait until the services are stopped and then kill
the backend, always in a fixed time in order to avoid blocks/hangs on
the system session logout.

Closes #5870.
Merge remote-tracking branch 'refs/remotes/ivan/bug/fix-system-logout-block' into develop
Enable keyring again
Merge remote-tracking branch 'chiiph/bug/properly_enable_keyring' into develop
Do not default to SecretService keyring
Merge remote-tracking branch 'chiiph/bug/more_keyring_fixes' into develop
Add cancel button for EIP connection.

Closes: #4035

This falls in the "quick" workaround category.

A proper state machine that extends the four basic connection states
is hence needed. We have to accomodate design to have a
connection-oriented state machine in the backend (I would favor a
twisted protocol for this), and a more lightweight one that conducts
the gui-level changes (ie, change the actions / buttons / labels
accordingly).

Since this "cancel" functionality has been long postponed, I chose
to do one more ugly hack here, that is, show and hide dance with a
button that just calls the bitmask-root to kill the vpn process. It
should work well enough until we get to the reorganization needed for a
clean process control for eip.
Merge remote-tracking branch 'refs/remotes/kali/feature/pseudo-cancel-eip' into develop