Allow mods to add to logic effect map (#9507)

* Allow mods to add to logic effect map

* Switch to being only a single add.

core/src/mindustry/logic/LogicFx.java

@@ -57,6 +57,12 @@ public class LogicFx{
         return map.get(name);
     }
 
+    /** Adds an effect entry to the map. */
+    public static void add(String name, EffectEntry entry){
+        entry.name = name;
+        map.put(name, entry);
+    }
+
     public static String[] all(){
         return map.orderedKeys().toArray(String.class);
     }