Replace font-kit

[sagudev]

font-kit and pathfinder crates are de facto unmaintained, and soon this will also be official, so it would be nice to migrate off them: https://servo.zulipchat.com/#narrow/channel/500774-tsc/topic/How.20to.20announce.20that.20we.20are.20going.20to.20stop.20working.20on.20crates.3F

All crates come from:

piet/piet-svg/Cargo.toml

Line 26 in 618083f

font-kit = "0.14.3"

[xStrom]

The path forward is probably fontique and it doesn't look like too much work. If someone wants to do it, I can review it.