Ability to click on links in pinned messages

### Your use case

#### What would you like to do?

I would like to click on the link that I just put into my pinned message.

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

As a workaround to not being able to put nice Markdown links into the room topic.

- #27915

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

Links are rendered in blue and with an underline. Clicking on them opens a new tab with the target of the link.

### Have you considered any alternatives?

Nice human-readable Markdown links in the room topic don't work.

### Additional context

This is probably the same for Web and Desktop, but might need follow ups for these tracking issues for the mobile implementations:

- https://github.com/element-hq/element-android/issues/357
- https://github.com/element-hq/element-ios/issues/4573