feat: extend universe_domain support

[danielbankhead]

For context, this is how universe_domain is passed to the clients via JSON:

google-auth-library-nodejs/src/auth/googleauth.ts

Lines 579 to 615 in e7b8029

	/**
	* Create a credentials instance using the given input options.
	* @param json The input object.
	* @param options The JWT or UserRefresh options for the client
	* @returns JWT or UserRefresh Client with data
	*/
	fromJSON(
	json: JWTInput | ImpersonatedJWTInput,
	options: RefreshOptions = {}
	): JSONClient {
	let client: JSONClient;
	options = options || {};
	if (json.type === USER_REFRESH_ACCOUNT_TYPE) {
	client = new UserRefreshClient(options);
	client.fromJSON(json);
	} else if (json.type === IMPERSONATED_ACCOUNT_TYPE) {
	client = this.fromImpersonatedJSON(json as ImpersonatedJWTInput);
	} else if (json.type === EXTERNAL_ACCOUNT_TYPE) {
	client = ExternalAccountClient.fromJSON(
	json as ExternalAccountClientOptions,
	options
	)!;
	client.scopes = this.getAnyScopes();
	} else if (json.type === EXTERNAL_ACCOUNT_AUTHORIZED_USER_TYPE) {
	client = new ExternalAccountAuthorizedUserClient(
	json as ExternalAccountAuthorizedUserClientOptions,
	options
	);
	} else {
	(options as JWTOptions).scopes = this.scopes;
	client = new JWT(options);
	this.setGapicJWTValues(client);
	client.fromJSON(json);
	}
	return client;
	}

🦕