@Effect()-decorated methods that return Promise instead of Observable should be supported

[Maximaximum]

It would be really awesome if the @Effect() decorator (and other decorators as well probably?) supported Promises, not just Observables as return values of the decorated functions. This way the @Effect() decorator behavior would be consistent with the behavior of the core ngxs @Action() decorator (see https://www.ngxs.io/concepts/state#async-actions).