[Widgets] Handle display logic (#1019)
* [Model Widget] Handle display logic
* format
* when disabled, hide compute btn, no placehlders
* correct placement of InferenceDisplayability labels
* "Inference Examples" label
* hide WidgetTimer when disabled on textGen widget
* rm unused vars
* fix a todo
* rm unused var
* filter examples with outputs when widget is disabled
* format
* rn
* rn
* use `<slot let:xyz>` syntax
