Add missing copy to fix ArrayIndexOutOfBoundException when invoke captureContinuation

[Rhython]

In the captureContinuation method, stack and stackAttribute are considered to be the same length. The ensureStackLength method does not copy stackAttributes with the new length, so calling captureContinuation after this will throw an ArrayIndexOutOfBoundException. I updated my project to use v1.8.0 and found this issue so I fixed it and create this pr.

[gbrail]

Is there a way that you can construct a test case for this? It's important that we have some way of tracking down possible regressions.

[Rhython]

Of course, I made a simplified reproduction code, but I'm not sure how to incorporate it into the unit test of the project.

public class TestRhino2 {

    private Scriptable scope;
    private Object continuation;

    public void await() {
        try (Context cx = Context.enter()) {
            throw cx.captureContinuation();
        }
    }

    public void execute(String source) {
        try (Context cx = Context.enter()) {
            scope = cx.initSafeStandardObjects();
            scope.put("t", scope, this);
            cx.executeScriptWithContinuations(cx.compileString(source, "test", 1, null), scope);
        } catch (ContinuationPending e) {
            continuation = e.getContinuation();
        }
    }

    public void resume(Object obj) {
        try (Context cx = Context.enter()) {
            cx.resumeContinuation(continuation, scope, obj);
        } catch (ContinuationPending e) {
            continuation = e.getContinuation();
        }
    }

    public static void main(String[] args) {
        TestRhino2 test = new TestRhino2();

        String js1 = """
                let mainMenu = [];
                let bonusMenu = [];
                // add enough items to inc stack size
                for (let i = 0; i < 30; i++) {
                    mainMenu.push(['MainMenu' + i, 'MainAction' + i]);
                    bonusMenu.push(['BonusMenu' + i, 'BonusAction' + i]);
                }
                Array.prototype.push.apply(mainMenu, bonusMenu) // this will cause ensureStackLength to be called
                let select = t.await() // this will cause ArrayIndexOutOfBoundsException
                """;
        test.execute(js1);
        test.resume(0);

    }

}