Removes usages of zone-based helpers such as `fakeAsync` , `tick`
`waitForAsync` as part of the migration to zoneless tests.
Completes the transition to zoneless.
(cherry picked from commit 7dfbacbcf8)
A util file is added to forms test package:
- it exposes simpleAsyncValidator, asyncValidator and asyncValidatorReturningObservable validators
- it refactors simpleAsyncValidator and asyncValidator to use common promise creation code
- it exposes currentStateOf allowing to get the validation state of a list of AbstractControl
Closes#37831
PR Close#38020
SkyZeroZx