Modules: Switch Module Closures to be AsyncGenerators

[AaravMalani]

This PR migrates foreign functions in the module types to represent AsyncGenerators instead of raw functions.

Rationale

This has been implemented to solve a re-entrancy issue for module function execution in CSE machines. If a module function needs to call a CSE closure, the CSE machine is stalled by the module function and cannot evaluate the closure

With the new update, the AsyncGenerator allows the module function to yield when it needs to evaluate a CSE closure.
For example

function f(x: TypedValue<DataType.CLOSURE>): AsyncGenerator<void, TypedValue<DataType.VOID>, undefined> {
    // NOTE: yield* is used since it delegates yields to the data handler on the runner side to decide when 
    // the closure needs to yield (aka, is a CSE closure)
    yield* closure_call_unchecked(x, []);
    return mVoid();
}

[gemini-code-assist]

Code Review

This pull request refactors closure execution and list accumulation to return AsyncGenerators instead of Promises, allowing deferred execution in CSE machines. The review feedback correctly identifies several outdated JSDoc @returns annotations in accumulate.ts and IDataHandler.ts that still reference Promise, and suggests a clearer phrasing for the new documentation in README.md.

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[gemini-code-assist]

The JSDoc @returns tag is outdated. It still states that the function returns a Promise, but the signature has been updated to return an AsyncGenerator. Please update the JSDoc to reflect this change.

[gemini-code-assist]

The JSDoc @returns tag for closure_call is outdated. It still documents the return type as a Promise, but it now returns an AsyncGenerator. Please update the JSDoc to reflect this change.

[gemini-code-assist]

The JSDoc @returns tag for closure_call_unchecked is outdated. It still documents the return type as a Promise, but it now returns an AsyncGenerator. Please update the JSDoc to reflect this change.

[gemini-code-assist]

The phrase "until the closure's return value is executed" is slightly confusing, as a return value itself is not executed. Consider rephrasing it to "until the closure's execution is completed and its return value is returned" or "until the closure is executed and its return value is obtained".