The _configSetClusterParameter command will be an internal command that is only accepted on config server primary nodes. It will instantiate the SetClusterParameterCoordinatorService to coordinate durably storing the provided parameter on a majority of nodes on all shard + config server replica sets. 

1. Define _configSetClusterParameter command via IDL
2. Implement behavior such that it is only accepted on the config server primary node.
3. Ensure that it can only be run by the internal system user so that 
4. Serialize such that only 1 command can run on the node at a time. The running command will instantiate the POS and wait for its response to reply with. All requests that come in-between will fail with ConflictingOperationInProgress.
5. Write an integration test to ensure that this command functions as expected when run directly on a config server primary.