feat: Add getEffectById to EffectManager (#29)

* Add getEffectById to EffectManager

Fixes #25.

* The template approach is better in practice

Author: phroggster

types/modules/effect-manager.d.ts

@@ -2,5 +2,6 @@ import { Effects } from "../effects";
 import EffectType = Effects.EffectType;
 
 export type EffectManager = {
+    getEffectById: <EffectModel>(effectId: string) => EffectType<EffectModel> | undefined;
     registerEffect: <EffectModel>(effectType: EffectType<EffectModel>) => void;
 };