fix: add animation frame for submitting answers after problem reset

[bra-i-am]

Fixes a timing bug where the Submit button remained enabled after clicking Reset on CAPA problems (SCQ, MCQ, and others).

When reset_internal receives the server response it calls render(response.html), which replaces the problem DOM via jQuery's .html(). The new HTML has no checked inputs, but browsers cache the checked state of form controls by name/id across a DOM replacement — so immediately after the swap :checked still returns true on the fresh inputs before the browser repaints. bind() runs synchronously inside render() and calls submitAnswersAndSubmitButton() right away; that function finds the inputs "checked" (stale cache), sets answered = true, and leaves the Submit button enabled.

The fix wraps a second submitAnswersAndSubmitButton() call in window.requestAnimationFrame, which defers execution until after the browser has painted the new frame. By that point the stale form state is cleared, :checked correctly returns false for all inputs, and the Submit button is disabled as expected.

Closes openedx/openedx-platform#36824

Testing instructions

1. Start a Tutor environment with this package installed as editable.
2. Switch the package to this branch
3. Navigate to a course unit with a Single Choice (SCQ) or Multiple Choice (MCQ) problem.
4. Submit an incorrect answer — the Submit button becomes enabled.
5. Click Reset.
6. Before: Submit button stays enabled and allows submitting with no selection.
7. After: Submit button is immediately disabled; it only re-enables once the learner selects an option.

Screencast

Before	After
Screencast.from.17-09-26.15.39.26.webm	Screencast.from.17-09-26.15.39.02.webm

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