Creates an object that contains the information required to perform HTTP Basic authentication.
a!httpAuthenticationBasic( username, password, preemptive )
username (ScsField): The username to use during the authentication. Created with a!scsField().
password (ScsField): The password to use during the authentication. Created with a!scsField().
preemptive (Boolean): Determines whether or not authentication credentials are sent only after a 401 Not Authorized response or, when true, before the system has challenged. Default: false.