Set mouse cursor style for links in message content

[gnprice]

When hovering on a link with a pointer capable of hover, one expects the style of the cursor to change. This isn't possible on a typical mobile device, so most users will never see it, but it'd be a neat small bit of polish to get it right anyway.

For a widget that's clickable, one takes care of this by wrapping it in MouseRegion(cursor: SystemMouseCursors.click, …) (docs: MouseCursor, SystemMouseCursors.click), as @sirpengi demonstrated at #287 (comment) .

For the links in our message content, it'll be more subtle, as discussed at #287 (comment) . But I think we can do it by setting TextSpan.mouseCursor.