[DMN Designer] Add support for 'parent' to DMNModelInstrumentedBase

DMNModelInstrumentedBase needs to support parent (like org.kie.dmn.model.v1_1.DMNModelInstrumentedBase) in order to correctly implement getPrefixForNamespaceURI(..) that is needed to set the QName prefix when setting data-types on nodes.

At the moment the QName for data-types in the UI is using the namespaceURI instead of the prefix as it is currently impossible to lookup a prefix from the namespaceURI (of the nodes' parents up to Definitions).

Changes required for this JIRA (split into sub-tasks when work starts):-

• Update XML->(kie)DMN->(ui)DMN model mapping in the marshaller
• Update the UI to set parent when adding nodes to the DRGElement and children
• Update code relating to "setting data-type" to lookup prefix for QName
• When creating a new Diagram we need to set up the basic default NameSpace contexts on the DMNDiagram's Defintions