src/vs/workbench/services/preferences/browser/preferencesService.ts/PreferencesService/openFolderSettings
class PreferencesService:	async openFolderSettings(options: IOpenSettingsOptions = {}): Promise<IEditorPane | undefined> {
		options = {
			...options,
			target: ConfigurationTarget.WORKSPACE_FOLDER
		};

		if (!options.folderUri) {
			throw new Error(`Missing folder URI`);
		}

		const folderSettingsUri = await this.getEditableSettingsURI(ConfigurationTarget.WORKSPACE_FOLDER, options.folderUri);
		if (!folderSettingsUri) {
			throw new Error(`Invalid folder URI - ${options.folderUri.toString()}`);
		}

		return this.open(folderSettingsUri, options);
	}