The goal is to add specifically EAP-WSC registrar side and it looks like
extending our EAP and EAPoL code to support both supplicant and
authenticator-side methods is simpler than adding just EAP-WSC as a
special case.
Since EAP-WSC always ends in an EAP failure, I haven't actually tested
the success path.
Replace the usage of eap_send_response() in the method implementations
with a new eap_method_respond that skips the redundant "type" parameter.
The new eap_send_packet is used inside eap_method_respond and will be
reused for sending request packets in authenticator side EAP methods.
