Move FunctionKind to CodeBlock

[HalidOdat]

Depends on #3439

Since the kind of the function is known at compile time, we can move it to CodeBlock's bitflags. This change allows us to simplify the logic of function creation. Remove GetAsyncArrowFunction, GetFunctionAsync and GetGeneratorAsync opcodes.

[github-actions]

Test262 conformance changes

Test result	main count	PR count	difference
Total	95,609	95,609	0
Passed	75,978	75,978	0
Ignored	18,872	18,872	0
Failed	759	759	0
Panics	0	0	0
Conformance	79.47%	79.47%	0.00%

[codecov]

Codecov Report

Attention: 46 lines in your changes are missing coverage. Please review.

Comparison is base (4b8ca76) 45.39% compared to head (1d1e441) 45.45%.

❗ Current head 1d1e441 differs from pull request most recent head 62f2f25. Consider uploading reports for the commit 62f2f25 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3440      +/-   ##
==========================================
+ Coverage   45.39%   45.45%   +0.05%     
==========================================
  Files         483      483              
  Lines       49787    49715      -72     
==========================================
- Hits        22602    22599       -3     
+ Misses      27185    27116      -69     

Files	Coverage Δ
boa_engine/src/bytecompiler/class.rs	16.33% <100.00%> (ø)
boa_engine/src/bytecompiler/function.rs	100.00% <100.00%> (ø)
boa_engine/src/bytecompiler/jump_control.rs	93.96% <100.00%> (ø)
boa_engine/src/bytecompiler/statement/mod.rs	91.17% <100.00%> (ø)
boa_engine/src/bytecompiler/statement/try.rs	91.20% <100.00%> (ø)
boa_engine/src/object/mod.rs	28.97% <ø> (ø)
boa_engine/src/vm/opcode/get/function.rs	54.83% <100.00%> (+12.90%)	⬆️
boa_engine/src/vm/opcode/mod.rs	5.00% <ø> (ø)
boa_engine/src/vm/opcode/push/class/mod.rs	66.66% <ø> (ø)
boa_engine/src/bytecompiler/mod.rs	67.60% <90.00%> (+0.80%)	⬆️
... and 9 more

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[raskad]

Very nice refactor!

[nekevss]

Looks fantastic! 😄 Really nice refactor!