Enable parallel hammer simulations

[colinschmidt]

Type of change: new feature

Impact: software change

Release Notes
Enable parallel simulations in hammer

[colinschmidt]

This is ready for review.
The chipyard changes are just to allow the user to use Hammer's yaml input directly and not override those keys based on BINARY when its empty.

[jwright6323]

What happens if you try to run power with no BINARY?

[colinschmidt]

If the user doesn't supply any Hammer yaml to set inputs to sim and doesn't set BINARY sim will just run the simulator with no input which in chipyard just quickly ends the simulation when FESVR detects no binary.
If the user doesn't supply any of the above and runs power the tool will just give static power reports. The current makefile generation in hammer doesn't directly support running power without running sim first, but the user can do this with a redo-power-par and setting the appropriate yaml keys.