privatise certain methods in aa_learner's

MetaAugment/autoaugment_learners/aa_learner.py

MetaAugment/autoaugment_learners/autoaugment.py

MetaAugment/autoaugment_learners/gru_learner.py

MetaAugment/autoaugment_learners/randomsearch_learner.py

MetaAugment/autoaugment_learners/ucb_learner.py

benchmark/scripts/util_04_22.py

.../MetaAugment_library/autoaugment_learners/aa_learners.rst

...generated/MetaAugment.autoaugment_learners.aa_learner.rst

...enerated/MetaAugment.autoaugment_learners.evo_learner.rst

...enerated/MetaAugment.autoaugment_learners.gru_learner.rst

...MetaAugment.autoaugment_learners.randomsearch_learner.rst

...enerated/MetaAugment.autoaugment_learners.ucb_learner.rst

docs/source/usage/autoaugment_helperclass.rst

test/MetaAugment/test_aa_learner.py

test/MetaAugment/test_gru_learner.py

test/MetaAugment/test_randomsearch_learner.py