Returns whether this device has a stored passkey ready to be used for sign-in
function hasStoredPasskey( client: ThirdwebClient, ecosystemId?: `ecosystem.${string}`,): Promise<boolean>;
the thirdweb client
let client: { readonly clientId: string; readonly secretKey: string | undefined;} & Readonly<ClientOptions>;
let ecosystemId: `ecosystem.${string}`;
let returnType: Promise<boolean>;
whether the device has a stored passkey