EAP peer: Add framework for external SIM/USIM processing

EAP peer: Add framework for external SIM/USIM processing

The new configuration parameter external_sim=<0/1> can now be used to
configure wpa_supplicant to use external SIM/USIM processing (e.g., GSM
authentication for EAP-SIM or UMTS authentication for EAP-AKA). The
requests and responses for such operations are sent over the ctrl_iface
CTRL-REQ-SIM and CTRL-RSP-SIM commands similarly to the existing
password query mechanism.

Changes to the EAP methods to use this new mechanism will be added in
separate commits.

Signed-hostap: Jouni Malinen <j@w1.fi>