Figure out function signature for `RenderedEffectSourceAnimationConfig["animation"]`

[JPMeehan]

In src/foundry/client-esm/canvas/sources/rendered-effect-source.d.mts, the animation callback is currently typed as AnyFunction because it's very unclear what the intended type is for the function.

    /**
     * The animation function that runs every frame
     * @privateRemarks TODO: Figure out if there's a better way to define the function
     */
    animation?: AnyFunction | undefined;
    ```