* Implement SetCredentials for MongoDB, adding support for static accounts
* rework SetCredentials to split from CreateUser, and to parse the url for database
* Add integration test for mongodb static account rotation
* check the length of the password results to avoid out-of-bounds
* remove unused method
* use the pre-existing test helper for this. Add parse method to helper
* remove unused command
* WIP on mongodb plugin
* Add mongodb plugin
* Add tests
* Update mongodb.CreateUser() comment
* Update docs
* Add missing docs
* Fix mongodb docs
* Minor comment and test updates
* Fix imports
* Fix dockertest import
* Set c.Initialized at the end, check for empty CreationStmts first on CreateUser
* Remove Initialized check on Connection()
* Add back Initialized check
* Update docs
* Move connProducer and credsProducer into pkg for mongodb and cassandra
* Chage parseMongoURL to be a private func
* Default to admin if no db is provided in creation_statements
* Update comments and docs
