Disconnected subgraph analysis for district network diagrams

* There is a new view called District Network Breakdown that can be used
to see the different disconnected subnetworks inside each district
network diagram.
* The view allows selecting the selected subnetworks on the actual
diagram to give the user an idea where they are
* The algorithm to calculate the disconnected subnetworks comes through
OSGi services (interface SubgraphProvider) and this change has no
implementation for the provider yet. It is on the Apros side for now
because the logic contains Apros-specific analysis.
* The district network diagram can now be opened and focused at certain
elements e.g. through CTRL+R open resource dialog by entering a district
network diagram element's name and pressing enter.

gitlab #11
gitlab #13

Change-Id: I98b9adfa589026530d84e65d5db08c0670349fa2