Websocket persistent notification: allow customizable links to different dashboards

**Is your feature request related to a problem? Please describe.**

The new websocket persistent notification actually provides a nice, quick shortcut to Home Assistant. However, after seeing it for a few hours, being told "Listening to Home Assistant via Websocket" is no longer really useful information.

I know the persistent notification must stay in order to keep Android from killing the app under pressure. That's fine. But as it is, the notification is using some of the most valuable and scarce UI real estate (and visible/attention space) to just show a basically useless static message and a rarely-useful configuration link.

This is part of several suggestions to improve this (linked by #2266).

**Describe the solution you'd like**

The current notification provides a handy shortcut to the overview. It would be nice to be able to have links to different HA panels, for quick access. Possible mockup:


**Describe alternatives you've considered, if any**

This could be configured either per-server or per-user in the app. I have no strong feelings about which is right.

Rather than action buttons, a more custom notification layout could be used. (Although AIUI Android is actively discouraging that now.)

**Additional context**

As noted, following on from https://github.com/home-assistant/android/issues/2266#issuecomment-1037329212_