Add botorch_mfkg use-case.

[shuds13]

Works in batch. May need to update for async.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 95 lines in your changes missing coverage. Please review.
✅ Project coverage is 76.17%. Comparing base (8c47657) to head (8ff42c3).
⚠️ Report is 3 commits behind head on develop.

Files with missing lines	Patch %	Lines
...semble/gen_funcs/persistent_botorch_mfkg_branin.py	0.00%	78 Missing ⚠️
libensemble/sim_funcs/augmented_branin.py	0.00%	17 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1608      +/-   ##
===========================================
- Coverage    77.04%   76.17%   -0.87%     
===========================================
  Files           79       81       +2     
  Lines         8325     8420      +95     
  Branches      1282     1286       +4     
===========================================
  Hits          6414     6414              
- Misses        1666     1761      +95     
  Partials       245      245              

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