KSPFGMRES: make KSPMonitor usage match KSPGMRES

KSPGMRES always monitors before an iteration has been taken, even if it is
determined that no iterations are necessary.  This change makes KSPFGMRES match
KSPGMRES.
Merge branch 'toby/ksp-fgmres-monitor' into maint

* toby/ksp-fgmres-monitor:
  KSPFGMRES: make KSPMonitor usage match KSPGMRES