DBus restart fixes
This MR improves both
portal-permissionstore plugins so that they can try to reconnect to DBus if the connection was closed, allowing them to keep working if the DBus service was restarted. Apart from this, the plugins now don't deactivate/activate themselves if the DBus connection is closed/connected, they will always stay active unless manually deactivated externally.
alsa.lua script has also been improved to destroy the ALSA monitor when the DBus connection is closed... and will re-create again a new ALSA monitor when the DBus connection is connected, which is needed in order to start reserving the devices again. All of this only happens if the plugin is loaded, otherwise the ALSA monitor is never destroyed.
Fixes #55 (closed)