Port escalier_old_codegen to work with new AST and type checker

[kevinbarabash]

TODO:

• [x] port codegen_d_ts()
• [ ] ~fix all the codegen tests~ I'm going to file separate tickets for all the issues

[codecov[bot]]

Codecov Report

Merging #674 (9aecd93) into main (e62ba14) will decrease coverage by 2.67%. The diff coverage is 54.21%.

:exclamation: Current head 9aecd93 differs from pull request most recent head a5e33c6. Consider uploading reports for the commit a5e33c6 to get more accurate results

@@            Coverage Diff             @@
##             main     #674      +/-   ##
==========================================
- Coverage   90.65%   87.98%   -2.67%     
==========================================
  Files         106      109       +3     
  Lines       22065    23817    +1752     
==========================================
+ Hits        20003    20956     +953     
- Misses       2062     2861     +799     

Files Changed	Coverage Δ
crates/escalier_ast/src/class.rs	100.00% <ø> (ø)
crates/escalier_ast/src/expr.rs	97.77% <ø> (ø)
crates/escalier_ast/src/literal.rs	35.13% <0.00%> (-41.34%)	:arrow_down:
crates/escalier_hm/src/folder.rs	83.98% <0.00%> (-2.71%)	:arrow_down:
crates/escalier_hm/src/infer.rs	91.72% <0.00%> (ø)
crates/escalier_hm/src/types.rs	80.59% <0.00%> (-0.35%)	:arrow_down:
crates/escalier_hm/src/unify.rs	82.63% <0.00%> (-0.35%)	:arrow_down:
crates/escalier_hm/src/util.rs	78.16% <0.00%> (-0.12%)	:arrow_down:
crates/escalier_hm/src/visitor.rs	33.33% <0.00%> (-0.84%)	:arrow_down:
crates/escalier_codegen/src/js.rs	50.24% <50.24%> (ø)
... and 5 more

... and 6 files with indirect coverage changes