Split off last bot modules

And dissolve AI namespace.
There would have been so little left in Common.AI,
that keeping it made no sense anymore.

OpenRA.Mods.Common/Traits/BotModules/CaptureManagerBotModule.cs

@@ -12,7 +12,6 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
-using OpenRA.Mods.Common.AI;
 using OpenRA.Traits;
 
 namespace OpenRA.Mods.Common.Traits