Add option to export Room Keys as in element-web / element-desktop

### Your use case

#### What would you like to do?
Ability to export room keys in element-x

#### Why would you like to do it?
Currently seeing lots of UTD messages in element-x. The only way to get UTD off is to share the Room Keys from the senders.

The element-web/element-desktop support this option, but not element-x

#### How would you like to achieve it?
Enable Room Keys export option.

### Have you considered any alternatives?

no

### Additional context

_No response_

### Are you willing to provide a PR?

Yes