fix(forms): ensure to emit statusChanges on subsequent value update…

[sonukapoor]

… / validations

This commit ensures that the updateValueAndValidity method takes the
asyncValidator into consideration to emit on the statusChanges observables.
This is necessary so that any subsequent changes are emitted properly to any
subscribers.

BREAKING CHANGE:

Previously if FormControl, FormGroup and FormArray class instances had async validators
defined at initialization time, the status change event was not emitted once async validator
completed. After this change, the status event is emitted into the statusChanges observable.
If your code relies on the old behaviour, you can filter/ignore this additional status change
event.

Closes #20424
Closes #14542

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/angular/angular/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Documentation content changes
• angular.io application / infrastructure changes
• Other... Please describe:

What is the current behavior?

Issue Number: N/A

What is the new behavior?

Does this PR introduce a breaking change?

• Yes
• No

Other information

[AndrewKushnir]

Thanks for adding tests @sonukapoor 👍

I've left a few comments (most of them are applicable to many tests), please have a look when you get a chance. Once the feedback is addressed, I will have another look.

Thank you.

[sonukapoor]

@AndrewKushnir All changes are done. The PR is ready for the second review.

[AndrewKushnir]

Initial Presubmit + Initial Global Presubmit.

[AndrewKushnir]

Hi @sonukapoor, thanks for additional changes. I've left a few more comments, please have a look when you get a chance. Thank you.

[sonukapoor]

@AndrewKushnir It's ready for another review. Thanks

[AndrewKushnir]

Thanks for updating tests @sonukapoor, great work 👍

I've a few more comments, they are mostly around comments/test descriptions, so I think we should move this PR to the "Ready for Review" state and perform a final round of review.

Thank you.

[AndrewKushnir]

Thanks for updating descriptions in tests, this is super helpful 👍

I've just left a comment on the last test, everything else looks great!

Since this is a change in behavior, could you please include a draft of the breaking changes note into the commit description (we can review and update it)?

[AndrewKushnir]

LGTM, thanks Sonu 👍

[AndrewKushnir]

Global Presubmit #2.

[AndrewKushnir]

Note to Caretaker: the global presubmit went well (only pre-existing failures), however since it's technically a breaking change, it might make sense to merge it and sync as a separate change (in case a rollback is needed). Thank you.

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