Slicer Visualization Header - Erase and List/Dropdown controls

[mgraff]

Whenever manipulating the formatting for the built-in Slicer visualization, we may want to turn on "Title" and turn off "Header" so we can have a custom header/title on the slicer. Unfortunately, the erase and list/dropdown controls are a part of the "Header" section. They should really be independent somehow so they don't get hidden when the header is turned off.