Object Writer V1 Demo Features

[adamperlin]

These are (hopefully) the last few features needed to get a usable wasm module from crossgen2 that we can use in our test harness. It adds:

• An offset for the data section to reserve space for a runtime stack
• A table section with no assigned elements
• Logic to generate wasm-level type signatures for any methods in the compilation

[kg]

Two quick TODOs:

• Export the memory
• Export the function table

[adamperlin]

Note: Full support for proper wasm-level signature generation (including by-value structs) will depend on #123515

[Copilot]

Pull request overview

Summary: This PR adds essential WebAssembly module features to the crossgen2 object writer to generate usable WASM modules for testing. The changes enable data section offsets for runtime stack allocation, add a table section for function references, and implement type signature generation for methods.

Changes:

• Introduces a data section offset (0x10000 / 64KB) to reserve space for runtime stack
• Adds table section support with configurable size based on method count
• Refactors export functionality to support multiple export types (function, table, memory, global)
• Implements WebAssembly type signature generation from .NET method signatures, mapping .NET types to WASM value types

[dotnet-policy-service]

Tagging subscribers to 'arch-wasm': @lewing, @pavelsavara
See info in area-owners.md if you want to be subscribed.

[kg]

I'd like to get this in as-is and do any necessary cleanup in followup PRs

[adamperlin]

I'd like to get this in as-is and do any necessary cleanup in followup PRs

That sounds good to me, I've mostly been working on follow up to this PR. This seems blocked on CI?

[adamperlin]

/ba-g infra failures