Use parley instead of low-level types (skrifa)

[simbleau]

It has recently become known to me that parley is the preferred crate for text setting and styling, and we should be using that for our text integration. Using the low-level crates like skrifa are not advised.

I don't have many good examples yet of parley in production use or how to migrate the code, so looking for help on this from linebender as a whole. Will likely revisit this in the Zulip if no one takes up the work.