Refactoring: ClientBulkWriteOperation

- Document the `doWithRetriesDisabled*` methods, leave `TODO-JAVA-5956` to fix them.
- Add `ClientBulkWriteCommandOkResponse`, use it instead of a generic `BsonDocument`.
- Naming of callbacks.
- Code formatting.

JAVA-5956, JAVA-6117, JAVA-6113, JAVA-6119, JAVA-6141

Author: stIncMale