Add support for Barracuda Spam Filter Mailing Queue

Feature Requests
1

Hi,

I have an feature request for the Barracuda Spam Filter Device in LibreNMS. I miss some graph where i can check the mailing queue of Barracuda, in our older system (Cacti) we had some plugin for it that made it possible.

The following SNMPTraps, I mean:
.1.3.6.1.4.1.2021.8.1.2.1 = STRING: InMailQueue
.1.3.6.1.4.1.2021.8.1.2.2 = STRING: OutMailQueue
.1.3.6.1.4.1.2021.8.1.2.3 = STRING: BounceMailQueue