Optimize widget discoverability

[skolmer]

Is your suggestion related to a problem? Please describe.

The current version of the element client contains a new icon at the top right when ever at least one widget is added to the room. For inexperienced users it is currently not easy to find available widgets that aren't pinned to the room. You have to click on an "info" icon at the upper right to access a panel where multiple features are listed and click there on a widget to open it or pin it to the room.

Describe the solution you'd like

We would like to have an option to add individual icons to the top right corner of element to directly access individual widgets. We understand that this can get quite messy so it should be limited to a fixed amount of icons and others should be hidden behind an ellipsis menu. However, if the system administrator wants to have standard widgets available to every user in the organization the homeserver admin should be allowed to override this and set specific widget icons to always visible.

[N1N74]

We could instead allow widgets to be displayed as individual rooms in communities for easy, intuitive access to widgets. I've heard guilded.gg has something like that for calendars, forums and schedules.
Since element is becoming more oriented towards community chat than room chat, this makes more sense to do.

Edit: I hear there won't be landing page for communities, but this would be more intuitive and easy to find anyway. Also takes care of #15741 for max vertical space.