Authenticate devices via Agent-Circuit-Id

Adjust FreeRADIUS SQL config to identify devices by their Agent-Circuit-Id instead of their User-Name

--- a/etc/raddb/mods-config/sql/main/mysql/queries.conf
+++ b/etc/raddb/mods-config/sql/main/mysql/queries.conf
@@ -35,7 +35,7 @@
 #	Else use hard-coded string "DEFAULT" as the user name.
 #sql_user_name = "%{%{Stripped-User-Name}:-%{%{User-Name}:-DEFAULT}}"
 #
-sql_user_name = "%{User-Name}"
+sql_user_name = "%{Agent-Circuit-Id}"
 
 #######################################################################
 # Default profile

Restart FreeRadius
```
systemctl restart radiusd
```

Insert new test user into radcheck and radusergroup (assumption QoS with id 1 already exists, device Agent-Circuit-Id is 0x0123456789ab)

INSERT INTO radcheck (username, attribute, op, value) VALUES ('0x0123456789ab', 'Auth-Type', ':=', 'Accept');
INSERT INTO radusergroup (username, groupname, priority) VALUES ('0x0123456789ab', 0, 1);
INSERT INTO radusergroup (username, groupname, priority) VALUES ('0x0123456789ab', 1, 1);