Alter launchers to pass env when starting a local step

[ankona]

This ticket ensures that an experiment with a workload manager will pass environment variables to unmanaged steps. This edge case occurs if a developer manually creates and attach a RunSettings instance instead of using the experiment.create_run_settings factory method.

Changes include:

• minor formatting (multi-line statements converted to single line)
• LocalStep environment is passed to task manager when task is unmanaged by launcher
• slurm-specific tests added to verify task run in popen inherits calling env

[codecov]

Codecov Report

Merging #329 (15b8d9f) into develop (4c741be) will decrease coverage by 0.13%.
The diff coverage is n/a.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #329      +/-   ##
===========================================
- Coverage    87.30%   87.18%   -0.13%     
===========================================
  Files           59       59              
  Lines         3522     3518       -4     
===========================================
- Hits          3075     3067       -8     
- Misses         447      451       +4     

Files Changed	Coverage Δ
smartsim/_core/launcher/local/local.py	94.00% <ø> (-0.45%)	⬇️
smartsim/_core/launcher/taskManager.py	77.24% <ø> (-2.40%)	⬇️

[ashao]

Small changes to ensure that the test doesn't fail on non-slurm machines. Other question, do you want to reserve adding tests for the other WLMs for later? It's a little challenging because of the combinations of WLMs and run commands

Thanks for digging into this one!

[ashao]

Thanks for the changes! Let's hold off on adding PBS+aprun tests since it might be a little harder to detect the availability of aprun.