Add functionality to turn off monitoring status of Models launched

[rickybalin]

This PR adds the ability to turn off monitoring of Models launched with experiment.start() by modifying the Controller and JobManager classes. With this update, experiment.start() takes an additional boolean argument determining whether to monitor the particular model or not. The argument is set to True by default, so it should not require any changes for the default behavior of monitoring all Models launched.

The PR also adds a method to PalsMpiexecSettings called set_launcher_args() to be able to add any launcher arguments to the mpiexec command.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.17%. Comparing base (d7d979e) to head (a62e971).
⚠️ Report is 25 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #788      +/-   ##
===========================================
- Coverage    83.91%   80.17%   -3.74%     
===========================================
  Files           83       78       -5     
  Lines         6284     6093     -191     
===========================================
- Hits          5273     4885     -388     
- Misses        1011     1208     +197     

Files with missing lines	Coverage Δ
smartsim/_core/control/controller.py	82.98% <100.00%> (-2.25%)	⬇️
smartsim/_core/control/jobmanager.py	93.75% <100.00%> (-0.41%)	⬇️
smartsim/experiment.py	85.02% <ø> (-0.86%)	⬇️

... and 39 files with indirect coverage changes

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[rickybalin]

@ashao, could I get some help getting this PR reviewed and merged? We need it for some functionality to stand up a "persistent" colocated DB, to which applications can connect and disconnect during a workflow. Thanks!

Please let me know if there are any issues.