Add separate PME rank SimulationWorkload flags

Added the complete set of flags that indicate whether separate PME ranks are used and what type of PP-PME communication is used.

These flags allow simplifications in the force schedule as well as reducing the use of the confusingly defined cr->duty for now in do_force().

The additional benefit is a reduced reliance on passing around commrec for checks related to parallelization.

Refs #3913 (closed)