Save controls when changing asset type in Asset Template

Right now, when you create an Asset Template with a specific asset type, then change that asset type, all controls inside of the Asset Template Panel get removed.

It would be better if changing the asset type did not remove any controls, but saved all of the controls and simply applied the new asset type.

This is especially useful when an asset can be more than one type and changing asset types should retain all of the existing work put into creating the Asset Template.