engine: add thorium_actor_log() function

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
Signed-off-by: George K. Thiruvathukal <gkt@cs.luc.edu>
genomics: use the new logging API in unitig_manager

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
engine: add time in thorium_actor_log()

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>
engine: add nanoseconds in thorium_actor_log()

Signed-off-by: Sébastien Boisvert <boisvert@anl.gov>