Imperative-Render: Support transition in-and-out for elements

[Nick-Lucas]

We need some appropriate callbacks and params which can be passed to rendered elements in order to support transitions. For instance those supported by MUI Modal's

Something roughly along these lines:

const render = AlertsRenderer.useImperativeRender()

function() {
  render(params => (
    <Modal open={params.open} onClose={params.startDestroy} onClosed={params.destroy} />
  ))
}