Implement closures - Githubissues

This PR implements the basics of closures.

The additions are shown in these new specification tests https://github.com/kaleidawave/ezno/blob/4591ca369cc8b0e7715f560759a48bd34b2a725d/checker/specification/specification.md?plain=1#L223-L284

This PR does several things to support them:

Record in the current environment that a function closes over a variable. When a function has and environment that closes over a variable this is recorded on the function. Additionally current values are recorded rather than being forgotten.
When calling this function, it creates a new ClosureId. Any objects or functions generated by the function carry the closure id.
- This is done in the same way as structural generics. For example, for type arguments we have Array<number>, for closure arguments we have func<#closure 1> etc (all held internally, syntax just for illustration. (this is similar to .create_new_object)
Additionally the initial values are specialized and put onto the current closure state, which (like regular variable properties) is on environment.facts (not the function)
When calling a closure this id is known and passed down when reading variables and setting variables. This id changes the value of the value under key (closure_id, reference) (rather than just reference)

I made this process up. I am not quite sure how engines actually implement it. With Ezno and things like events I am trying to abstract things and reduce overhead. Running the exact same things done in synthesis every function call is off the table... And these need a few fix see follow up issue #56

This PR also tidies some stuff up

Printing uses a single buffer and catches cycles
Moved some files and functions around (got rid of an intermediate call_... function)
Some temp any stuff around parent variables
Probably some smaller other stuff

kaleidawave / ezno

Implement closures #55