[tune] Dragonfly Optimizer (#5955)

* Add sample example

* Copy relevant lines of ask from inherited Optimizer

* Ignore strategy

* Additional changes

* Add DragonflySearch for tune connector for Dragonfly

* Add example and fix small errors

* lint

* Remove skopt references

* Update example based off of Dragonfly changes

* Edit example for final Dragonfly edits

* Formatting and documentation edits

* Add documentation and add to test pipeline

* Address PR comments

* Fix Jenkins test

* Adjust Dragonfly to PR#7366

* Lint

* fix_tests

Co-authored-by: Richard Liaw <rliaw@berkeley.edu>

docker/examples/Dockerfile

@@ -14,6 +14,6 @@ RUN pip install -U h5py  # Mutes FutureWarnings
 RUN pip install --upgrade bayesian-optimization
 RUN pip install --upgrade hyperopt==0.1.2
 RUN pip install ConfigSpace==0.4.10
-RUN pip install --upgrade sigopt nevergrad scikit-optimize hpbandster lightgbm xgboost torch torchvision tensorboardX
+RUN pip install --upgrade sigopt nevergrad scikit-optimize hpbandster lightgbm xgboost torch torchvision tensorboardX dragonfly-opt
 RUN pip install -U tabulate mlflow
 RUN pip install -U pytest-remotedata>=0.3.1