Add an informational message when a user tries to open an already opened project (#13853)

extensions/data-workspace/src/services/workspaceService.ts

@@ -121,6 +121,8 @@ export class WorkspaceService implements IWorkspaceService {
 				if (vscode.Uri.file(relativePath).fsPath === projectFile.fsPath) {
 					newWorkspaceFolders.push(path.dirname(projectFile.path));
 				}
+			} else {
+				vscode.window.showInformationMessage(constants.ProjectAlreadyOpened(projectFile.fsPath));
 			}
 		}