Add botorch_mfkg use-case.

[shuds13]

Works in batch. May need to update for async.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 108 lines in your changes missing coverage. Please review.
✅ Project coverage is 76.08%. Comparing base (8c47657) to head (dae7ff5).
⚠️ Report is 5 commits behind head on develop.

Files with missing lines	Patch %	Lines
...semble/gen_funcs/persistent_botorch_mfkg_branin.py	0.00%	91 Missing ⚠️
libensemble/sim_funcs/augmented_branin.py	0.00%	17 Missing ⚠️

Additional details and impacted files

@@ Coverage Diff @@## develop #1608 +/- ##
===========================================
- Coverage 77.04% 76.08% -0.97% 
===========================================
Files 79 81 +2 Lines 8325 8433 +108 Branches 1282 1290 +8 ===========================================
+ Hits 6414 6416 +2 - Misses 1666 1773 +107 + Partials 245 244 -1 

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