Make Base implement IScopedNode - phase 1

[Kasdejong]

Description

This first step makes POCO's implement ITypedElement. Since we no longer supply an ITypedElement.Definition, we had to patch some of the parsers to get all unit-tests back to work. In the end, these changes to the parsers will be reverted, they are just made to be able to continue testing with our extensive set of tests on ITypedElement.

Related issues

2894, #2895

Testing

Tested by making Base.ToTypedElement() point to this implementation. This is temporary.

[Kasdejong]

Serialization is still binary breaking, but not source breaking. It now takes Base instead of Resource

[Kasdejong]

Note: We will investigate to what extent this is breaking after we work our way through the. [TemporarilyChanged] annotations.