Create Extensions to validate collections

[Insomniak47]

We could use some extensions that validate some common functionality that we might want to guarantee with collections:

Things I was considering were:

• IsNotEmpty()

• HasSomeNumberOfElements [Wip on the name]

• AllElements(Predicate)

• NoElements(Predicate)

• SomeElements(Predicate,int Count)

Should probably split this into constituents

[Insomniak47]

Now that I think about it just the first two. The other ones are better suited to IEnumerable extensions since they need to enumerate the whole collection. Has some number of elements should have an ICollection overload since it's a difference between O(1) and O(n)