progress bar and minor QOL fixes

[Waqar-ukaea]

Very small PR which adds a more detailed progress bar to the ParticleSimulation::Execute(). Previous iteration would check if 25%, 50% and 75% of the total work had been completed. New implementation abstracts out to a separate method that calls a for loop over 10 iterations (in practices could be any denomination of 100) and checks if workComplete == (i*TotalWork)/10. Perhaps this would cause some slowdown. Before merging this in with master maybe some profiling should be completed. Full changelist below:

Changelist

• New private ParticleSimulation::update_progress_indicator() method that calls to update the progress indicator every 10% that is complete. This works for both the dynamic_mpi and serial runs (may need a different function for no_load_balanced_mpi)
• Added a new flag to the main function that queries the json for an "global_params": {"mpi_timings"} parameter. When present and set to true AEGIS will print individual mpi rank timings to console (useful for debugging slow processes)
• By default AEGIS will always print total elapsed wall time on process 0 but will only print other wall times when this flag is present
• Renamed member variable ParticleSimulation::exeType to ParticleSimulation::execution_type to be more explicit in its intent
• ParticleSimulation::mpi_particle_stats() method is now only called when "aegis_params": {"print_mpi_particle_stats": true}