Improve update performance of DynamicTreeTableViewer

For models with larger data dictionaries, the update of the data
dictionary can become slow enough that editing element names becomes
difficult. This commit changes the DynamicTreeTableViewer such that
not the whole tree is re-build on every update. This solves the
issue with the data dictionaries.

Signed-off-by: Ulrich Schöpp <schoepp@fortiss.org>
Issue-Ref: 4192