Chats List: Notification badges

### Your use case

#### What would you like to do?
Currently, for Rooms set to "Mentions and Keywords only", both the @ symbol and green dot appear simultaneously when you're mentioned.
- This can create confusion - showing 2 indicators for 1 type of message.

Only showing the @ symbol would be enough for these Rooms.

#### Why would you like to do it?
It can help a user quickly determine the type of activity in a room by differentiating between:
- Rooms set to **'all messages'** that you were simply mentioned in
**VS**
a Room set to **'Mentions. . .only'**

#### How would you like to achieve it?
- Rooms set to **"Mentions and Keywords only"** should **only use the @ symbol**.
- Rooms set to **"All messages"** should show a green dot **only for unread message excluding mentions/keywords**.

### Have you considered any alternatives?

https://github.com/element-hq/element-meta/issues/2878#issue-3096767759

### Additional context

In rooms set to “Mentions and Keywords only,” users have already set to receive directly related notifications (mentions and keywords only) , so displaying both indicators for a single mention can diminish individual meaning.

### Are you willing to provide a PR?

No