fix: Magic NPCs now use spell range (#1870)

### Summary
- Drastically streamlines the spell targeting by collapsing the target classes into a single `SpellTarget<T>` class.
- Moves TargetRange to the spell itself so it can be used by MageAI.
- Changes range check in MageAI to use TargetRange. This should fix target acquisition bugs

Projects/UOContent/Spells/Targeting/ISpellTarget.cs

@@ -1,7 +1,6 @@
-namespace Server.Spells
+namespace Server.Spells;
+
+public interface ISpellTarget<in T> where T : IPoint3D
 {
-    public interface ISpellTarget
-    {
-        ISpell Spell { get; }
-    }
+    ITargetingSpell<T> Spell { get; }
 }