Annotate Wasm AST nodes (Instrs) with bytecode position metadata for tracing/debugging

[bbyalcinkaya]

This PR adds support for position-annotated instructions in the Wasm AST, enabling execution traces to carry bytecode position metadata for debugging.

Changes

• Update py-wasm to the version that supports this feature (currently linked to a branch; will point to the released version once the corresponding py-wasm PR is merged)
• Add #instrWithPos(inner: Instr, posStart: Int, posEnd: Int) syntax
• Add execution rule to unwrap the wrapper:

rule <instrs> #instrWithPos(I, _, _) => I ... </instrs>

• Update AST translation in wasm2kast to handle wrapped instructions

Notes

• This PR depends on the corresponding py-wasm PR (Wrap instructions with position info for tracing py-wasm#6) introducing InstructionWithPos and will not function correctly until that PR is merged.

[RaoulSchaffranek]

Can you clarify if postStart and postEnd start at 0 or 1, and if they're inclusive or exclusive?
Also, it might be worth considering using an offset+length pair instead of a start+end pair for consistency with Python coding conventions.

[bbyalcinkaya]

Thanks. I switched to an offset + length representation and added more comments.