* Add CancelTokenKey for uniquely identifying cancelations of Connections associated with an OwnerUri and ConnectionType string.
* Update ConnectionInfo to use ConcurrentDictionary of DbConnection instances. Add wrapper functions for the ConcurrentDictionary.
* Refactor Connect and Disconnect in ConnectionService.
* Update ConnectionService: Handle multiple connections per ConnectionInfo. Handle cancelation tokens uniquely identified with CancelTokenKey. Add GetOrOpenConnection() for other services to request an existing or create a new DbConnection.
* Add ConnectionType.cs for ConnectionType strings.
* Add ConnectionType string to ConnectParams, ConnectionCompleteNotification, DisconnectParams.
* Update Query ExecuteInternal to use the dedicated query connection and GetOrOpenConnection().
* Update test library to account for multiple connections in ConnectionInfo.
* Write tests ensuring multiple connections don’t create redundant data.
* Write tests ensuring database changes affect all connections of a given ConnectionInfo.
* Write tests for TRANSACTION statements and temp tables.
