Prevalue sources also includes element types

[bjarnef]

When defining a prevalue source it is also possible to select element types, but I don't think element types are supported - only nodes rendered in tree.

If both document types and element types where supported the property should probably say "Content Type" instead.

Umbraco v10.0.1
Umbraco Forms v10.0.3

Maybe this should also use the tree picker instead like in MNTP configuration to keep it a bit more consistent with core UI.

[AndyButland]

Will remove element types and ensure this list is ordered for the upcoming release.