Proposal: Allow onInit/afterViewInit/afterContentInit to return observables

[dummdidumm]

It would be great if formly would support observables on the hooks onInit afterViewInit and afterContentInit. If an observable is returned from one of the hooks, Formly would automatically subscribe to that observable until the field is destroyed. This would free users from subscribing to the observable and handling the onDestroy-hook themselves.

Example usage:

fields = [{
   ...
   hooks: {
      // Patch value of some other form control every time this value changes
      // subscription and unsubscribe is handled by formly
      onInit: field => field.formControl.valueChanges.pipe(
                    tap(value => field.form.patchValue({someOtherField: value})
                 )
   }
 },
...
];

[aitboudad]

This issue has been fixed and released as part of v5.7 release.

Please let us know, in case you are still encountering a similar issue/problem.
Thank you!