Update FortiOS - Add support to managed Switches and APs

Add support for new OID that allow you to pull a Fortigate to get all the connected FortiSwitches and FortiAPs and their status, IP, etc.

https://docs.fortinet.com/document/fortigate/6.4.0/new-features/87594/snmp-queries-to-the-fortigate-switch-controller-for-fortiswitch-and-port-information-6-4-2

Discovery:
https://p.libren.ms/view/9d938222

Poller:
https://p.libren.ms/view/e8adff16

snmpwalk
https://p.libren.ms/view/21761d5a

snmpwalk specific to a FortiSwitch:
https://p.libren.ms/view/b214d982

snmpwalk for FortiAP names and status:
https://p.libren.ms/view/2d06b315

Thanks in advance!