Include actual value in exception message of `CollectionIsEmptyAssertion`

[PhilippNaused]

When the IsEmpty() assertion fails, the error message doesn't say what elements were found. Only that the collection wasn't empty.

[Test]
public async Task Test1()
{
    List<int> a = [1, 2, 3];
    await Assert.That(a).IsEmpty();
}

Results in:

AssertionException: Expected to be empty
but collection contains items

It would be very helpful if the message contained the string representation of the elements.
Other assertion types (like IsEquivalentTo) return information about the mismatched elements, so I would expect IsEmpty to do the same.