Cleaned up DFS interface

Only depth-limited invocation is retained as that's the only one being
used
Refactoring only

Moved coordinates
Extracted logging to separate class for DFS
Refactored search monitors

No longer injected as injection was not used. Extracted common stuff to
common superclass in preparation for BFS counterpart
Reworked launcher apps a bit
Moved BFS and DFS to separate packages
Created launcher traits for DFS and BFS apps
Improved DFS logging