Disconnect Object Explorer node when session is disconnected from SQL Tools Service (#3249)

* WIP

* WIP

* Send disconnect event to OE

* Bump dataprotocol to 0.2.9

* Cleanupps

* Address a couple feedback

src/sqltest/stubs/objectExplorerProviderTestService.ts

@@ -30,6 +30,10 @@ export class ObjectExplorerProviderTestService implements sqlops.ObjectExplorerP
 
 	}
 
+	public registerOnSessionDisconnected(handler: (response: sqlops.ObjectExplorerSession) => any): void {
+
+	}
+
 	public registerOnExpandCompleted(handler: (response: sqlops.ObjectExplorerExpandInfo) => any): void {
 
 	}