Some kind of semi-persistent notification about widgets when an admin sets them in the room layout

### Steps to reproduce

I was watching OTWSU today, its room is/was configured with a countdown widget and a stream widget. In the default view, it was impossible to tell there are widgets if you missed the timeline message about them being added much earlier (that would be #21218):

As a "workaround", a cunning room admin could in principle set everybody's layout to his own layout, however I think force-opening a pinned or maximized widget on everyone isn't always the best style (though it might fit here it may not always).

What I instead expected was to see the "4 leaf clover" widget icon somewhere potentially with a notification dot "hey there are widgets you haven't yet looked at".

What I really would like to see is a way for room admins to suggest widgets without updating the room which will show up as a persistent notification for everybody else. Similarly if I closed a widget from a "suggested widget layout" we have today (these may not be implemented in a way this is easy to do, but would still like to see it).

### Outcome

#### What did you expect?
Notification about widgets

#### What happened instead?
Just have to guess

### Operating system

arch

### Application version

20220205

### How did you install the app?

aur

### Homeserver

1.52

### Will you send logs?

No