message: Fix incorrect setting persistence logic.
  User can chose to store "globally" or "per-workspace." Fix the code to _actually_ do this correctly.
  [Fix
diff: @@ -247,14 +247,12 @@ class ExtensionManager implements vscode.Disposable {
  // Use cancelled. Do nothing.
  return;
  }
  - let config: vscode.WorkspaceConfiguration;
  + const config = vscode.workspace.getConfiguration(undefined, ws.uri);
  + let config_target = vscode.ConfigurationTarget.Global;
  if (choice.persistMode === 'workspace') {
  - config = vscode.workspace.getConfiguration(undefined, ws.uri);
  - } else {
  - console.assert(choice.persistMode === 'user');
  - config = vscode.workspace.getConfiguration();
  + config_target = vscode.ConfigurationTarget.WorkspaceFolder;
  }
  - await config.update('cmake.configureOnOpen', chosen.doConfigure);
  + await config.update('cmake.configureOnOpen', chosen.doConfigure, config_target);
  });
  rollbar.takePromise('Persist config-on-open setting', {}, persist_pr);
  should_configure = chosen.doConfigure;
  