Keep custom visuals in desktop

[michaelm3]

Once adding custom visuals to PowerBI desktop, have them always available in the chart well when loading PowerBI desktop. That way we do not have to keep loading them, they should be added and stay added.

[loufarho]

This is especially import to have them centralized so that when an update comes out, we update it once. Once centralized, then I want to be able to see updates and then install the update!