function renderingFor(ctrWrapper) {
		return window.customElements.whenDefined(ctrWrapper.getMetadata().getTag()).then(nextUIUpdate);
	}
Helper function to await the rendering of the given web component control wrapper.
Additionally awaits the definition of the custom-element if needed.

@param {module:sap/ui/core/WebComponent} ctrWrapper the control wrapper sub class
@returns {Promise} a Promise resolving once the given control wrapper has finished rendering