Implements:
- UUIDs: https://www.pivotaltracker.com/story/show/182931137
- Comments: https://www.pivotaltracker.com/story/show/182981779
- Type annotations and signatures: https://www.pivotaltracker.com/story/show/182497454
- Fix getter names (https://github.com/enso-org/enso/pull/3627#discussion_r940887460).
# Important Notes
- I can't fully test UUIDs; I have tested that the data obtained in Rust matches my understanding of how the format is supposed to work. What remains to be tested is that the data in Java matches the way the old parser handles the format. So @JaroslavTulach, let me know if you see any cases where I'm not returning the same values.
- This implementation of type annotations and signatures accepts any expression in type context. It would probably be nice to narrow this down at some point, but for now I have no design info on what specifically should be allowed in type expressions; this implementation should be at least an incremental improvement.
