Add a built-in mcmc sampler

.dictionary.txt

.pre-commit-config.yaml

bilby/bilby_mcmc/__init__.py

bilby/bilby_mcmc/chain.py

bilby/bilby_mcmc/flows.py

bilby/bilby_mcmc/proposals.py

bilby/bilby_mcmc/sampler.py

bilby/bilby_mcmc/utils.py

bilby/core/result.py

bilby/core/sampler/__init__.py

bilby/core/sampler/base_sampler.py

bilby/core/utils/io.py

bilby/gw/prior.py

optional_requirements.txt

setup.py

test/bilby_mcmc/chain.py

test/bilby_mcmc/proposals.py

test/bilby_mcmc/sampler.py

test/integration/sampler_run_test.py