Get reference to clicked element in modal onShow callback

Would be nice get a reference to the element that was clicked (if available) to trigger Modal.show() in the callback function.

Something like:

<button id="modalToggleId" data-modal-target="modalEl" data-modal-toggle="modalEl">...</button>

<div id="modalEl">...</div>

<script>
    modalOptions = {
        onShow: (clickedElement: HTMLElement | undefined) {
            if (clickedElement) {
                clickedElement.innerHtml = "Clicked";
            }
        },
    }
    const modal = new Modal(document.getElementById("modalEl"), modalOptions);
</script>

Start by locating the Modal.show entry point and the onShow callback implementation described in the issue. Trace how the clicked element is available, then verify that onShow receives it when Modal.show() is triggered through the data-modal-toggle markup; done means the callback can safely use the element when one exists.