1) In backends, ensure they are now using TokenPolicies
2) Don't reassign auth.Policies until after expmgr registration as we
don't need them at that point
Fixes#4829
* redoing connection handling
* a little more cleanup
* empty implementation of rotation
* updating rotate signature
* signature update
* updating interfaces again :(
* changing back to interface
* adding templated url support and rotation for postgres
* adding correct username
* return updates
* updating statements to be a list
* adding error sanitizing middleware
* fixing log sanitizier
* adding postgres rotate test
* removing conf from rotate
* adding rotate command
* adding mysql rotate
* finishing up the endpoint in the db backend for rotate
* no more structs, just store raw config
* fixing tests
* adding db instance lock
* adding support for statement list in cassandra
* wip redoing interface to support BC
* adding falllback for Initialize implementation
* adding backwards compat for statements
* fix tests
* fix more tests
* fixing up tests, switching to new fields in statements
* fixing more tests
* adding mssql and mysql
* wrapping all the things in middleware, implementing templating for mongodb
* wrapping all db servers with error santizer
* fixing test
* store the name with the db instance
* adding rotate to cassandra
* adding compatibility translation to both server and plugin
* reordering a few things
* store the name with the db instance
* reordering
* adding a few more tests
* switch secret values from slice to map
* addressing some feedback
* reinstate execute plugin after resetting connection
* set database connection to closed
* switching secret values func to map[string]interface for potential future uses
* addressing feedback
* Start work on context aware backends
* Start work on moving the database plugins to gRPC in order to pass context
* Add context to builtin database plugins
* use byte slice instead of string
* Context all the things
* Move proto messages to the dbplugin package
* Add a grpc mechanism for running backend plugins
* Serve the GRPC plugin
* Add backwards compatibility to the database plugins
* Remove backend plugin changes
* Remove backend plugin changes
* Cleanup the transport implementations
* If grpc connection is in an unexpected state restart the plugin
* Fix tests
* Fix tests
* Remove context from the request object, replace it with context.TODO
* Add a test to verify netRPC plugins still work
* Remove unused mapstructure call
* Code review fixes
* Code review fixes
* Code review fixes
* Fix cassandra tests, explicitly set cluster port if provided
* Update cassandra.yml test-fixture
* Add port as part of the config option, fix tests
* Remove hostport splitting in cassandraConnectionProducer.createSession
* Include port in API docs
* 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
