Allow BasemapLayerListWidget to toggle Visible Elements

[TimPurdum]

https://developers.arcgis.com/javascript/latest/api-reference/esri-widgets-BasemapLayerList.html#visibleElements

BasemapLayerListWidget should have the ability to show or hide the following elements:

• Status Indicators
• Base Layers
• Reference Layers (#288 )
• Errors