"Insert link" should detect if the clipboard holds a valid link, and immediately insert it

### Your use case

The markdown popup on text is nice, but I think it could be nicer if the insert link popup verifies the clipboard with a link regex, and just puts it in, it'd save a little `ctrl-v` press.

### Have you considered any alternatives?

_No response_

### Additional context

_No response_

Start by locating the insert link popup and its clipboard handling in the Element web client. Check how the popup currently accepts links, then determine how valid clipboard content should trigger immediate insertion and how that behavior can be verified. Done means a valid clipboard link is inserted without an extra paste action, while invalid clipboard content leaves the normal flow unchanged.

Written by the indexing model from the issue text.