Add support for uiprop decorator
in order to fully use the rendering scheme:
` @uimodel("comp-x') class X { @uielement("comp-y", {slot: "top"}) prop1: "value1"
@uiprop("prop-name") prop2: "value2" } `
should render into:
<comp-x prop-name="value2"> <comp-y slot="top" value="value1"></comp-y> </comp-x>