style text for label formatter (and other formatters?)

[e00E]

I'm using a custom Plot::label_formatter. In my formatter I emit multi line text that I would like to be aligned. Usually I would use a monospace font to accomplish that but there is no option to do this because the formatter returns a plain String.

[bircni]

This was already mentioned a while ago: https://github.com/emilk/egui/pull/1235/files#r803985498