Implement core disposal logic for explicit resource management

[abhinavs1920]

This Pull Request fixes/closes #4445 .

Make using actually dispose ( continued work )

Follow-up to my last PR (#4649) that added parsing.

Now when a block ends, resources get cleaned up properly.

• New bytecodes: AddDisposableResource + DisposeResources + PushDisposalScope
• VM now has a disposal stack + scope tracking
• Bytecompiler adds resources after each using and cleans up at end of blocks

Works like:

{
  using file = openFile();
} // ← auto disposed here

{
  using a = one();
  using b = two();
} // disposes b then a

{
  using outer = ...;
  { using inner = ...; } // inner first
} // then outer

using x = null; // just skips, no crash

[github-actions]

Test262 conformance changes

Test result	main count	PR count	difference
Total	52,963	52,963	0
Passed	50,070	50,070	0
Ignored	2,072	2,072	0
Failed	821	821	0
Panics	0	0	0
Conformance	94.54%	94.54%	0.00%

Tested main commit: baaadfeeaf4a64f34e82cbbb9fee3ed4013495c0
Tested PR commit: d3aa12ee836a4cee8789ee029a94db77d11f65b2
Compare commits: baaadfe...d3aa12e

[codecov]

Codecov Report

❌ Patch coverage is 39.47368% with 69 lines in your changes missing coverage. Please review.
✅ Project coverage is 59.11%. Comparing base (6ddc2b4) to head (d3aa12e).
⚠️ Report is 858 commits behind head on main.

Files with missing lines	Patch %	Lines
core/engine/src/vm/opcode/global.rs	0.00%	33 Missing ⚠️
core/engine/src/vm/flowgraph/mod.rs	0.00%	16 Missing ⚠️
core/engine/src/vm/code_block.rs	8.33%	11 Missing ⚠️
...engine/src/vm/opcode/disposal/dispose_resources.rs	55.55%	8 Missing ⚠️
core/engine/src/bytecompiler/mod.rs	50.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #5079       +/-   ##
===========================================
+ Coverage   47.24%   59.11%   +11.86%     
===========================================
  Files         476      567       +91     
  Lines       46892    62783    +15891     
===========================================
+ Hits        22154    37113    +14959     
- Misses      24738    25670      +932     

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