Feature/report field solve mpi time

• Move field timer out of getfield_local to call site

  Needed to more fairly capture the field update done separately in some situations.

• Mover field timer out of getfield to call site.

  Enables us to capture the field update step as well for fairness.

• Record fraction of field solve time spent in MPI

• Report field solve mpi time

As the field solve can often be what appears to limit scaling at high core counts, it can be useful to see how much time is spent in mpi vs computation.