Expand editability of Item Description for WebMaps

[bligtvoet]

First of all, I am really glad with the new ArcGIS Assistant, it is much more user friendly when working with multiple portals. Now on to my idea. I know that editing the item description json is very dangerous. However I think that it would be very nice to have edit options in the item description based on the type of item that is currently being edited.

For example, I am currently migrating a WebMap from our Test environment to our Production environment. The WebMap extent has been changed on Test and I want to copy this new extent over to the existing Prod WebMap. Apparently this property is read only right now which I don't think is very logical. It would be nice if this could be changed. If it isn't possible to implement this, it would be nice to instead flag which properties are edible in the json editor.