feat(MfSimulationList): add functionality to parse the mfsim.lst file

[jdhughes-usgs]

• add testing for MfSimulationList

[codecov]

Codecov Report

Merging #2005 (e89a41d) into develop (16183c3) will increase coverage by 1.7%.
The diff coverage is 91.8%.

Additional details and impacted files

@@            Coverage Diff            @@
##           develop   #2005     +/-   ##
=========================================
+ Coverage     70.9%   72.7%   +1.7%     
=========================================
  Files          258     259      +1     
  Lines        57456   58955   +1499     
=========================================
+ Hits         40791   42915   +2124     
+ Misses       16665   16040    -625     

Files	Coverage Δ
flopy/mf6/utils/__init__.py	100.0% <100.0%> (ø)
flopy/mf6/utils/mfsimlistfile.py	91.7% <91.7%> (ø)

... and 103 files with indirect coverage changes

[wpbonelli]

guess this is because virtual memory is only used for mf6 parallel at the moment — once flopy has more parallel support a parallel test case could be added to check virtual memory usage I imagine