add config ALLOW_ADMIN_EMAIL_LOGIN and implement password-less SOGo login admins

data/conf/nginx/templates/sogo.auth_request.template.sh

@@ -0,0 +1,7 @@
+if printf "%s\n" "${ALLOW_ADMIN_EMAIL_LOGIN}" | grep -E '^([yY][eE][sS]|[yY])+$' >/dev/null; then
+    echo '
+auth_request /sogo-auth-verify;
+auth_request_set $user $upstream_http_x_username;
+proxy_set_header x-webobjects-remote-user $user;
+'
+fi