If-else chaining

[kevinbarabash]

This works at both the expression level and the type level.

[codecov[bot]]

Codecov Report

Merging #643 (7904bcc) into main (24e3717) will increase coverage by 0.17%. Report is 1 commits behind head on main. The diff coverage is 97.54%.

@@            Coverage Diff             @@
##             main     #643      +/-   ##
==========================================
+ Coverage   90.52%   90.70%   +0.17%     
==========================================
  Files         101      101              
  Lines       20889    21009     +120     
==========================================
+ Hits        18910    19056     +146     
+ Misses       1979     1953      -26     

Files Changed	Coverage Δ
crates/escalier_ast/src/expr.rs	100.00% <ø> (ø)
crates/escalier_hm/src/infer.rs	90.53% <93.75%> (+0.02%)	:arrow_up:
crates/escalier_hm/src/util.rs	70.89% <94.52%> (+2.26%)	:arrow_up:
crates/escalier_ast/src/type_ann.rs	100.00% <100.00%> (ø)
crates/escalier_hm/src/unify.rs	80.47% <100.00%> (-0.20%)	:arrow_down:
crates/escalier_parser/src/expr_parser.rs	97.46% <100.00%> (+0.03%)	:arrow_up:
crates/escalier_parser/src/type_ann_parser.rs	94.57% <100.00%> (+0.79%)	:arrow_up:

... and 5 files with indirect coverage changes