Assert.ContainsSingle should accept non-generic collections

[AtolagbeMuiz]

Summary

Assert.ContainsSingle should accept non-generic IEnumerable collections like ArrayList, Stacks e.t.c. just the way Assert.Contains and Assert.DoesNotContain accept non-generic collection overload.

Current Behaviour

Assert.ContainsSingle throws compile time error because it only accepts generic collections.

[AtolagbeMuiz]

@Youssef1313 Just discovered we don't have this for Assert.ContainsSingle.. is this a feature the team will like to have, I will like to work on it...

[Youssef1313]

I think it makes sense to add. @nohwnd @engyebrahim any objection?

[nohwnd]

Seems okay to me, unless adding it will make the user less likely to use the generic overload.