AssetsAddAnd effect #103
Description
asset stores aren't the most reasonable resources to deal with in a cloning/mapping style that current resource effects provide. Would be inefficient as well since asset stores can be some of the larger resources in a bevy app. This issue is for adding an AssetsAddAnd effect for the most common mutable assets store use case: adding an asset from memory. Should take an impl FnOnce(Handle<A>) -> impl Effect closure, similar to AssetServerLoadAnd.