Prevent allocation of field names

[HalidOdat]

This PR makes the CodeBlock store JsStrings in the names field instead of Identifier (which is a wrapper around Sym), This is done because once we resolve the sym and get the &[u16] we allocate a JsString on every field access in the worst case and at best if it's part of the static strings array we do a HashMap lookup.

Ran the benchmarks locally and there was a 2% to 10% increase in performance in some of the benchmarks.

The performance increase can be better seen by running the quickjs benches:

Main

PROGRESS Richards
RESULT Richards 19.8
PROGRESS DeltaBlue
RESULT DeltaBlue 21.9
PROGRESS Encrypt
PROGRESS Decrypt
RESULT Crypto 27.9
PROGRESS RayTrace
RESULT RayTrace 76.8
PROGRESS Earley
PROGRESS Boyer
RESULT EarleyBoyer 67.8
ERROR RegExp TypeError: not a constructor
undefined
PROGRESS RegExp
PROGRESS Splay
RESULT Splay 99.4
PROGRESS NavierStokes
RESULT NavierStokes 6.28
SCORE 32.6
Uncaught Error: Benchmark had 1 errors

PR

PROGRESS Richards
RESULT Richards 21.0
PROGRESS DeltaBlue
RESULT DeltaBlue 23.0
PROGRESS Encrypt
PROGRESS Decrypt
RESULT Crypto 28.4
PROGRESS RayTrace
RESULT RayTrace 81.2
PROGRESS Earley
PROGRESS Boyer
RESULT EarleyBoyer 69.2
ERROR RegExp TypeError: not a constructor
undefined
PROGRESS RegExp
PROGRESS Splay
RESULT Splay 101
PROGRESS NavierStokes
RESULT NavierStokes 6.33
SCORE 33.7
Uncaught Error: Benchmark had 1 errors

[github-actions]

Test262 conformance changes

Test result	main count	PR count	difference
Total	94,601	94,601	0
Passed	73,298	73,298	0
Ignored	17,540	17,540	0
Failed	3,763	3,763	0
Panics	0	0	0
Conformance	77.48%	77.48%	0.00%

[raskad]

Looks like a good change. Nice improvement on the benchmarks.

[Razican]

Looks good, nice optimization!

[codecov]

Codecov Report

Merging #2901 (d0a1a9a) into main (e3d2056) will decrease coverage by 0.01%.
The diff coverage is 52.94%.

@@            Coverage Diff             @@
##             main    #2901      +/-   ##
==========================================
- Coverage   51.90%   51.90%   -0.01%     
==========================================
  Files         428      428              
  Lines       43113    43097      -16     
==========================================
- Hits        22378    22368      -10     
+ Misses      20735    20729       -6     

Impacted Files	Coverage Δ
boa_engine/src/vm/code_block.rs	56.84% <0.00%> (ø)
boa_engine/src/vm/flowgraph/mod.rs	0.00% <0.00%> (ø)
boa_engine/src/vm/opcode/define/class/getter.rs	0.00% <0.00%> (ø)
boa_engine/src/vm/opcode/define/class/method.rs	0.00% <0.00%> (ø)
boa_engine/src/vm/opcode/define/class/setter.rs	0.00% <0.00%> (ø)
boa_engine/src/bytecompiler/mod.rs	63.85% <100.00%> (+0.05%)	⬆️
boa_engine/src/vm/opcode/define/own_property.rs	87.50% <100.00%> (-0.60%)	⬇️
boa_engine/src/vm/opcode/delete/mod.rs	80.55% <100.00%> (-1.03%)	⬇️
boa_engine/src/vm/opcode/get/property.rs	85.71% <100.00%> (-0.50%)	⬇️
boa_engine/src/vm/opcode/set/property.rs	70.12% <100.00%> (-0.89%)	⬇️