Implement Buccaneer Valiant special ability

Adds the ability for the buccaneer valiant to spawn a ship that rams
enemies and smashes them. Next to a script that triggers the ship skill
a few other changes had to be made:
- Force movement behavior server side calculation and sync
- The ship has no physics volume so the FindValidTargets for behaviors
had to be altered to allow ControllablePhysics entities to find entities
within their area. The "target_self" AOE flag has been used to replicate
the old behavior.

dScripts/BuccaneerValiantShip.h

@@ -0,0 +1,6 @@
+#pragma once
+#include "CppScripts.h"
+
+class BuccaneerValiantShip : public CppScripts::Script {
+    void OnStartup(Entity *self) override;
+};