Added Enchantment.conflictsWith() and EnchantmentTarget.includes(). Addresses BUKKIT-1159 and addresses BUKKIT-1160

By: Celtic Minstrel <celtic.minstrel.ca@some.place>

paper-api/src/test/java/org/bukkit/configuration/file/TestEnchantment.java

@@ -47,4 +47,9 @@ public class TestEnchantment extends Enchantment {
         return true;
     }
 
+    @Override
+    public boolean conflictsWith(Enchantment other) {
+        return false;
+    }
+
 }