Fix Ops Studio issue 97 where query connection is dropped (#549)

- Fixes https://github.com/Microsoft/sqlopsstudio/issues/97.
- This should fix the bulk of the issues reported by users since it's the 1st use of this connection in the query code path.
- Implemented the fix in the connection service. This will always open a connection when calling `GetOrOpenConnection`. I cannot see a reason why the connection returned from this should ever be closed.
- resolve issues in both this code path and the edit data code path since both use this method.

test/Microsoft.SqlTools.ServiceLayer.UnitTests/Utility/TestObjects.cs

@@ -216,6 +216,7 @@ namespace Microsoft.SqlTools.ServiceLayer.UnitTests.Utility
         public override void Close()
         {
             // No Op
+            this._state = ConnectionState.Closed;
         }
 
         public override void Open()
@@ -225,6 +226,7 @@ namespace Microsoft.SqlTools.ServiceLayer.UnitTests.Utility
             {
                 throw new Exception("Invalid credentials provided");
             }
+            this._state = ConnectionState.Open;
         }
 
         public override string ConnectionString { get; set; }