feat(forms): add control status classes to form groups

[kara]

Previously, status classes were only added to elements with individual form control directives like formControlName and ngModel.

This PR adds status classes to group-based form control directives like formGroupName, ngForm, etc.

** Before **

<form [ngClass]="{'invalid': f.invalid}" #f="ngForm">  <!-- add invalid class yourself -->
   <input name="first" ngModel required>
</form>

** After **

<form>    <!-- form already has ng-invalid class automatically -->
   <input name="first" ngModel>
</form>

This should not be a breaking change, but note that if you are selecting for all ng-invalid classes globally, this may affect your styles.

[vikerman]

Running TAP Presubmit...

[vikerman]

TAP green. Merging...

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