Federated logout

[etortec]

It seems like auth-spa-js 1.1.0 currently does not support telling auth0 to perform a federated logout. There seems to be no way to pass the required federated query parameter since the LogoutOptions interface does not allow this:

auth0-spa-js/src/global.ts

Lines 162 to 179 in 5f94633

	interface LogoutOptions {
	/**
	* The URL where Auth0 will redirect your browser to after the logout.
	*
	* > Note that if the `client_id` parameter is included, the
	* `returnTo` URL that is provided must be listed in the
	* Application's "Allowed Logout URLs" in the Auth0 dashboard.
	* However, if the `client_id` parameter is not included, the
	* `returnTo` URL must be listed in the "Allowed Logout URLs" at
	* the account level in the Auth0 dashboard.
	*/
	returnTo?: string;
	/**
	* The `client_id` of your application.
	*/
	client_id?: string;
	}

Am i missing something? If not, can you please add an option to support auth0's federated logout?