Parse 'new' keyword for constructing new instances

[kevinbarabash]

This only handles parsing of new expressions. Type checking will be handled in a separate PR.

[codecov[bot]]

Codecov Report

Merging #711 (d6fbeff) into main (7a8a68a) will decrease coverage by 0.15%. The diff coverage is 77.14%.

@@            Coverage Diff             @@
##             main     #711      +/-   ##
==========================================
- Coverage   85.31%   85.16%   -0.15%     
==========================================
  Files          61       61              
  Lines       11730    11761      +31     
==========================================
+ Hits        10007    10016       +9     
- Misses       1723     1745      +22     

Files	Coverage Δ
crates/escalier_ast/src/expr.rs	97.87% <100.00%> (+0.04%)	:arrow_up:
crates/escalier_codegen/src/js.rs	78.65% <ø> (ø)
crates/escalier_hm/src/infer.rs	92.19% <ø> (ø)
crates/escalier_parser/src/expr_parser.rs	97.21% <100.00%> (+0.03%)	:arrow_up:
crates/escalier_parser/src/parser.rs	98.08% <100.00%> (+<0.01%)	:arrow_up:
crates/escalier_parser/src/token.rs	100.00% <ø> (ø)
crates/escalier_lsp/src/semantic_tokens.rs	0.00% <0.00%> (ø)
crates/escalier_ast/src/visitor.rs	55.88% <56.25%> (-2.68%)	:arrow_down:

... and 4 files with indirect coverage changes