Alternate Poller IP instead of Hostname (#10981)

* optional alternative poller ip

* add missing schema update

* .

* enhance API Call 'add_device' with overwrite_ip key

* .

* .

* updating docs

includes/html/api_functions.inc.php

@@ -405,6 +405,9 @@ function add_device(\Illuminate\Http\Request $request)
     } else {
         return api_error(400, 'You haven\'t specified an SNMP version to use');
     }
+
+    $additional['overwrite_ip'] = $data['overwrite_ip'] ?: null;
+
     try {
         $device_id = addHost($hostname, $snmpver, $port, $transport, $poller_group, $force_add, 'ifIndex', $additional);
     } catch (Exception $e) {