Use node predicate correctly

Summary:
Check node predicate before adding a node

A local node predicate could have been set before so we need
to check each time a node is added to the data storage if this node
is also relevant for the tree model.

Test Plan:
currently we are only using the simple tree model
inside the QmitkDataStorageViewerTestView.
Here no node predicate is set.
This could be tested by enabling the mentioned plugin and
call m_Controls.treeInspector->SetNodePredicate with something meaningful.

Reviewers: floca, O3 MITK Reviewer Group II

Reviewed By: floca, O3 MITK Reviewer Group II

Subscribers: kalali, floca

Maniphest Tasks: T29360

Differential Revision: https://phabricator.mitk.org/D734