[FEATURE] Buttons should accept e.g. a StyledSpan for formatting the lables

When adding keyboard shortcuts to the actions buttons have, it seems difficult to express the user that the binding exists.

One easy way would be to have a styled button (with e.g. one highlighted character, easily expressed with markdown), but unfortunately that's not supported at the moment. Buttons themselves could also have a way to add bindings to them, and then a way to show those bindings in the UI, but it would be a more complex solution.

There doesn't seem to be an alternative, other than making a custom implementation of a button.