Preview before sharing

### Your use case

#### What would you like to do?

#2984 is adding a way to receive elements (file / text) from other applications but once the room is selected there is no preview, and the data is sent to the room.

This can be a problem since it does not give a way to validate the data which will be sent.

Text could be previewed, or if only one room is selected (note: it's not possible to select multiple rooms right now), the text composer could be fill with the text and the message not sent, so that the user can edit and then send or just cancel the operation. Note that this can interfere if there is a not sent draft in the room (support for draft is coming).

Image and other files: a preview of the data can be displayed, with a way to remove some items. Also image could be cropped, rotated, but this can be handled separately (this is tracked by #2676).

Note that this also apply for picking items from other apps (AKA send attachment): currently it's only possible to pick one item and there is a preview but with no edition action.

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

Better user experience

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

Create design for screen preview and implement it.

### Have you considered any alternatives?

_No response_

### Additional context

_No response_

### Are you willing to provide a PR?

No