Support for OSC8 hyperlink styling

[zx8]

The original PR (#1928) implementing OSC8 hyperlink states:

[...] the underline only shows up on hover + ctrl/command. I think we can improve this behavior for OSC8 specifically in the future because the nature of OSC8 is that the TUI program wants it to be a link.

I couldn't find an issue or discussion formally tracking this feature request, so I'm starting a discussion.

As stated, an underline is shown once you hold ctrl/command and hover over a link, but this is bad for hyperlink discoverability, i.e. today, I wasn't aware that a tool I was using automatically created useful hyperlinks until I unrelatedly held the command key while moving my mouse over the text.

It would be neat to be able to configure how hyperlinks are styled. For me, a dotted underline is what I'm most familiar with, but any kind of styling that would make it clearer that some text is actually clickable without having to manually hold a modifier and hover over it is fine with me.