feat: add bindings for v8::WasmModuleCompilation

[bartlomieju]

Summary

Add Rust bindings for the new experimental v8::WasmModuleCompilation class from v8/include/v8-wasm.h, providing an interface for asynchronous WebAssembly module compilation (e.g. for source phase imports).

Bindings provided

• WasmModuleCompilation::new() / Default — create a new compilation
• on_bytes_received(&mut self, data: &[u8]) — feed wasm bytes (callable from any thread)
• finish(self, scope, caching_callback, resolution_callback) — finalize compilation on the main thread; the resolution callback receives Result<Local<WasmModuleObject>, Local<Value>> along with &Isolate for creating Global handles
• abort(self) — cancel compilation
• set_has_compiled_module_bytes(&mut self) — signal cached module bytes are available
• set_more_functions_can_be_serialized_callback(...) — register a serialization callback
• set_url(&mut self, url: &str) — set source URL before finishing
• Drop cleans up the C++ allocation; Send is implemented (V8 allows cross-thread usage)

Implementation details

• Resolution callback lifetime is managed via shared_ptr<void> with a custom deleter on the C++ side, which correctly handles std::function copy semantics when V8 internally copies the callback into its Resolver
• Rust side uses Option<Box<dyn FnOnce>> so the trampoline can .take() the closure (FnOnce semantics) without freeing the outer allocation, which is ref-counted by shared_ptr
• Serialization callback uses the same shared_ptr<void> pattern
• Isolate pointer is captured in the Rust closure rather than threaded through C++
• Caching callback function pointer is passed directly to V8 without wrapping

Test plan

• wasm_module_compilation — compiles a minimal wasm module, finishes, asserts the result via Global handle
• wasm_module_compilation_abort — compiles and aborts without finishing

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