RxJS 8 support

[e-oz]

I would like to know contributors' opinions about how difficult it would be to replace usage of rxjs/Notification in @ngrx/store library (Notification was removed in RxJS 8).

[timdeschryver]

I think most of the steps are already taken, which is using the const N, E, and C instead of Notification. Why the question? Do you spot something that could be difficult here?

[e-oz]

Only because current @ngrx/store is incompatible with rxjs/8-alpha. If it's handled already in some separate branch - good to know!

[timdeschryver]

To be clear, there's currently not a branch that updates RxJS to v8.

[e-oz]

So, affected files are in modules/effects/src/:
act.ts
effect_notification.ts
effect_sources.ts

They import Notification class from "rxjs".
This class was deprecated in RxJS 7 and removed from 8.

I suppose, we could create an interface or a class "Notification" in modules/effects/src/, something like

export interface Notification<T> {
  hasValue: boolean;
  kind: 'N' | 'E' | 'C';
  value?: T;
  error?: any;
}

and just edit the imports in 3 files.

If you think that it's ok - I'm ready to create a PR. If you have a better idea or I'm missing some important details - please let me know.

[timdeschryver]

Because it's removed I'm not sure if we should create our own.
Instead, we could use the ObservableNotification interface from RxJS.

[e-oz]

By your suggestion: PR #3407