Request to add Pepperpot / MGL Cyborg in multiplayer.

[Chewbakka-Wakka]

In terms of the in-game model, simple:

Attach the other unused arm with the same mortar model as Grenadier.
Then it can use alternating fire from each arm.

We should expand upon Cyborg units to have more readily available options.
Better for those Cyborg only games.
At this time, only 1 artillery type of unit exists as the Grenadier Cyborg.