Add EAP methods in wifi.proto

To help find the root cause of high authentication failure rate in enterprise network, add EAP method and authentication phase2 method in connection event metrics.

Bug: 150237135
Test: manual
Test: atest com.android.server.wifi
Merged-In: I7f3268b2842783f99c0a43d8b4996d0a7dd46c6e
Change-Id: Id4ac7947871785d16b81c0806986f54d64fdb0ce