Helper function to create a named list used as the claim of a JWT payload. See https://tools.ietf.org/html/rfc7519#section-4.1 for details.
jwt_claim(iss = NULL, sub = NULL, aud = NULL, exp = NULL, nbf = NULL,
iat = unclass(Sys.time()), jti = NULL, ...)
(Issuer) Claim, should be rfc7519 'StringOrURI' value
(Subject) Claim, should be rfc7519 'StringOrURI' value
(Audience) Claim, should contain one or rfc7519 'StringOrURI' values
(Expiration Time) Claim, should be rfc7519 'NumericDate' value
(Not Before) Claim, should be rfc7519 'NumericDate' value
(Issued At) Claim, should be rfc7519 'NumericDate' value
(JWT ID) Claim, optional unique identifier for the JWT
additional custom claims to include