Ability to share hazel programs via URL

[disconcision]

Encode (some of) the state of a hazel editor as a URL parameter.

Initial version of this can be very simple, ala: https://www.scottantipa.com/store-app-state-in-urls

Initially you could just encode the text representation of a hazel program. this will be somewhat slow to load due to slow parsing, and won't (currently) retain projectors, but would give us a basis to work off