Chat room position should be restored after program restart

### Description

Chat room positon won't be saved after program restart
### Steps to reproduce

When you open a room and **scroll up for a long time**.
Changed to another room and change back , the position is saved.
**But** after program restart the position is lost.
It becomes hard to read very old information because every time the program start the position is at the newest date.

Logs being sent: yes/no

### Version information

- **Platform**: web (in-browser) or desktop?

For the web app:

- **Browser**: Chrome, Firefox, Safari, Edge? which version?
- **OS**: Windows, macOS, Ubuntu, Arch Linux, etc?
- **URL**: develop.element.io / app.element.io / somewhere else? If a private server, what version of Element Web?

For the desktop app:

- **OS**: Windows, macOS, Ubuntu, Arch Linux, etc?
- win7 x64
- **Version**: 1.x.y
1.7.27

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- remember scroll position
- maintain scroll position
- same point in timeline when switching rooms
- remember room position
- scroll offset