thorium_transport: move the code that prints the transport configuration

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
thorium_node: print information about transport system

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
assembly_graph_store: get a starting vertex using a cleared flag

Link: https://github.com/GeneAssembly/biosal/issues/836
Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>