Reinstate People and Favorites to Sidebar (not room list)

### Steps to reproduce

Open Element after new update.

### Outcome

#### What did you expect?
In the previous version of the UI, there was the option to pin "people" and "favorites" to the sidebar together with the spaces. By sidebar, I mean the panel all the way on the left, where your profile picture and spaces reside. By enabling these, you always had quick access to them, independently of the space or chat you were in at the moment. You also received notifications for those quick categories - a blip appeared over one of the sidebar icons, so you instantly knew if you received a notification in a favorite room or a private chat room, which was very handy.
#### What happened instead?
This feature was removed altogether in the update that added the new room list, which is confusing, because this feature concerns the sidebar, not the room list. The option to enable this disappeared from both "quick settings" and "all settings". This is a major regression for my usecase and I had to disable the new room list in labs.

Pictures compare the quick settings before and after this update.

### Operating system

_No response_

### Browser information

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### URL for webapp

_No response_

### Application version

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### Homeserver

_No response_

### Will you send logs?

Yes