Object Explorer: Refresh OE node if database restored (#607)

* refresh OE node if restored

* refresh OE when task is completed

* check task id for restore

src/sql/parts/registeredServer/common/objectExplorerService.ts

@@ -63,6 +63,8 @@ export interface IObjectExplorerService {
 	isFocused(): boolean;
 
 	onSelectionOrFocusChange: Event<void>;
+
+	getServerTreeView(): ServerTreeView;
 }
 
 interface SessionStatus {
@@ -417,4 +419,8 @@ export class ObjectExplorerService implements IObjectExplorerService {
 	public isFocused(): boolean {
 		return this._serverTreeView.isFocused();
 	}
+
+	public getServerTreeView() {
+		return this._serverTreeView;
+	}
 }