shill: Ethernet: Send EAPOL logoff and logon

Use newly created "EAPLogoff" and "EAPLogon" commands in
wpa_supplicant to de-authenticate and speed authentication
on 802.1x wired networks respectively.  Add small fixes to
make sure that logoff happens during "Unload" and eap
credential changes.

CQ-DEPEND=CL:48803
BUG=chromium:234290
TEST=New unit tests.  Modified autotest
network_8021xWiredAuthentication tests logoff/logon using
profile pop/push (see https://gerrit.chromium.org/gerrit/48806).

Change-Id: Ic9f6e74371e7f57bd3f28b1a68be5fc603da0fdd
Reviewed-on: https://gerrit.chromium.org/gerrit/48802
Reviewed-by: Christopher Wiley <wiley@chromium.org>
Reviewed-by: mukesh agrawal <quiche@chromium.org>
Tested-by: Paul Stewart <pstew@chromium.org>
Commit-Queue: Paul Stewart <pstew@chromium.org>
diff --git a/ethernet_eap_service.cc b/ethernet_eap_service.cc
index f22f321..59e410f 100644
--- a/ethernet_eap_service.cc
+++ b/ethernet_eap_service.cc
@@ -42,6 +42,10 @@
   manager()->ethernet_eap_provider()->OnCredentialsChanged();
 }
 
+bool EthernetEapService::Unload() {
+  Service::Unload();
+  manager()->ethernet_eap_provider()->OnCredentialsChanged();
+  return false;
+}
+
 }  // namespace shill
-
-