FPGATrackSimGNN, add Junction Aware Connected Component to make roads

These changes add an alternative method to build roads from FPGATrackSimHits in FPGATrackSimGNN. If the Junction Aware CC method is selected, roads are built with a custom version of the connected components algorithm that outputs roads with no junctions. To do so, a custom version of BGL's Breadth First Search is used, configured such that hits connected by an edge (after cutting low score edges) are assigned to the same component and, in case of multiple inwards/outwards edges, multiple roads are constructed, one for each in/out edge.