Change shutdown listeners (#4282)

* change shutdown to use proper notification

* change to use storage service

* remove unused imports

* fix test

* change shutdown methods to private

* remove unusde imports

* fix tests

* formatting

src/sql/platform/capabilities/common/capabilitiesService.ts

@@ -131,6 +131,8 @@ export class CapabilitiesService extends Disposable implements ICapabilitiesServ
 			this.cleanupProviders();
 		});
 
+		_storageService.onWillSaveState(() => this.shutdown());
+
 		this._register(extentionManagementService.onDidUninstallExtension(({ identifier }) => {
 			const connectionProvider = 'connectionProvider';
 			let extensionid = getIdFromLocalExtensionId(identifier.id);
@@ -239,7 +241,7 @@ export class CapabilitiesService extends Disposable implements ICapabilitiesServ
 		}
 	}
 
-	public shutdown(): void {
+	private shutdown(): void {
 		this._momento.saveMemento();
 	}
 }