Port 100+ integration tests from dotnet/runtime

[theolivenbaum]

Ported over 100 tests from the dotnet/runtime repository to H5.Compiler.IntegrationTests. Focused on BCL types (System.Type, System.String, System.Delegate, Enums) and JIT Methodical tests (Arrays, FlowControl, Structs). Added a Python script to automate the conversion, handling namespace removal and shim injection. Fixed a concurrency issue in H5Compiler.cs causing NullReferenceException during parallel test execution.

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PR created automatically by Jules for task 2330704274978824853 started by @theolivenbaum

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