Polling cleanup, fix PHP warnings (#13460)

* Fix warnings up to Arbos

* fixes a-c

* a-r

* a-vrp

* There and back again

* Update test data, couple fixes

* PHPSStan fixes

* style fixes, and fix Asyncos, whoops

* flip serial back.......

* less bogus data

* Poweralert sysName during polling too

* make sure things are calculated in the correct order

* fix style and bad nullables

* update test data

* A comple more conversions

* cambium ptp, misc, and hardware_mib

* remaining except vmware-esxi

* Fixes

* Update baseline

* fixes and fix up baseline

* adjust SnmpQueryMock to upstream options change

* data corrections

* restore slashes

* correctly handle all options input in SnmpQueryMock

* undo ftos changes

* restore vccodec sysDescr

LibreNMS/Util/Rewrite.php

@@ -457,9 +457,9 @@ class Rewrite
      * If given input is an IPv6 address, wrap it in [] for use in applications that require it
      *
      * @param  string  $ip
-     * @return string
+     * @return string|null
      */
-    public static function addIpv6Brackets($ip): string
+    public static function addIpv6Brackets($ip): ?string
     {
         return IPv6::isValid($ip) ? "[$ip]" : $ip;
     }