io.snapcraft.SessionAgent can send notifications in Do Not Disturb mode, as well as when blocked at the Application level

Hello beautiful xfce maintainers -

I'm having an issue that is well described in this AskUbuntu question - How to block Snap update notifications on XFCE?. Basically, io.snapcraft.SessionAgent is able to send pesky update notifications regardless of the Notifications filter rule, as well as if Do Not Disturb is on.

How to test:

• Install the Firefox Snap package
• Filter io.snapcraft.SessionAgent from sending notifs, or enter do not disturb
• Wait for a Firefox update
• Get the notification

If this is a bug in Snapcraft, let me know and I'll recreate the issue there.

Thanks!