[MIRROR] Pre-vox modpack cleanup.

[SkyratBot]

Original PR: NebulaSS13/Nebula#1050

This is basically all the non-modpack changes needed for the vox modpack PR.

• De-voxes the remaining vox stuff in the codebase (guns, slugs, shuttle waypoints).
• Moves the raider antagonist datum into the heist folder along with the skipjack console.
• Allows the entire heist folder to be unticked, removing the map and antag datum.
• Adds heist include to tradeship and away site testing map defines.
• Repaths titanium to remove the /plasteel from the path, removes trailing alloy_product var.