Add a new style that supports tooltips

[edgararuiz]

It would be useful to add tooltip messages that show up when the text is hovered over. At this time, style_hyperlink() can be used to get that effect, but @hadley suggested that it would be useful to support it properly.

cli::style_hyperlink("label", "tooltip text")

https://github.com/r-lib/cli/assets/77294576/5bd83928-9818-447b-a782-44d99a5f70a5