ilukyanchikov has created PR #1494: PYTHON-2267: Allow UUID key_id to be passed to ClientEncryption.encrypt in mongo-python-driver

Issue Text:
Modify the ClientEncryption.encrypt API to accept native UUIDs directly. [jira task](https://jira.mongodb.org/projects/PYTHON/issues/PYTHON-2267)
I validated my changes with the TestExplicitSimple cases. pytest -v -s test/test_encryption.py::TestExplicitSimple
I tried to run all the test_encryption.py tests, but some of the tests require environment credentials, and as far as I understand, I need MongoDB Enterprise for mongocryptd support.