Add option to hide or display unread messages in muted rooms

### Your use case

#### What would you like to do?

Add an option to hide or display unread messages for muted rooms in the room list at the user's will.

#### Why would you like to do it?

There seems to be 2 type of users out there who use muted rooms differently: some of them think of muted rooms as 'rooms I don't want to get any notifications from but want to know when something happens' and others as 'rooms I don't usually care about, but I may visit from time to time so I don't leave them but I don't want to be bothered by them at all'.

This is tracked in https://github.com/element-hq/element-meta/issues/2358.

#### How would you like to achieve it?

By adding an option in Settings -> Notifications screen to enable or disable this, as well as analytics to try to find out what most users prefer.

### Have you considered any alternatives?

No.

### Additional context

_No response_

### Are you willing to provide a PR?

Yes