update IdenticalTest to test ArrayObject context parameters
remove type hint from Validator\Identical::isValid()

The type hint was introduced in 7bcd59a8 and causes PHP errors when
passing in ArrayObject context parameters. Remove the type hint and
make sure the passed context is either an array or an ArrayObject
instance.
fix CS
#6592 - allowing `ArrayAccess` instead of `ArrayObject` instances for `$context`
#6592 - invalid data was not being used/skipped: data provider executes invalid cases one by one instead
#6592 - adding missing `@dataProvider` annotation
Merge branch 'hotfix/#6592-identical-validator-array-hint-removal' into develop

Close #6592