Second-click when joining a room to stop accidental joins

### Your use case
"the issue I've had was when searching the public directory for specific keywords and pressing enter to search without realising 'join' was highlighted, so just hitting enter on my keyboard automatically joined me to the room."

#### What would you like to do?
When joining a room present the user with a second click so that users can't accidentally join rooms (especially if they're 'bad')

#### Why would you like to do it?
Raised by a member of the Element team in an [internal room](https://matrix.to/#/!ZCWYLfAKXolsPWObuZ:matrix.org/$Hp9g9fjIkS-nGvIg-X0bgEYP2_MgUXCktof5r4aE9rc?via=matrix.org&via=element.io&via=t2l.io)

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

### Have you considered any alternatives?

_No response_

### Additional context

_No response_