ComparableTypeAssertions should have BeOneOf method

[jez9999]

Because ComparableTypeAssertions doesn't contain BeOneOf, the following code doesn't work:

float testFloat = 12f;
var testTuple = (1, 2);

testFloat.Should().BeOneOf(12f, 13f); // Works
testTuple.Should().BeOneOf((1, 2), (1, 3)); // Doesn't work

I don't see any technical reason why the latter shouldn't work, so how about adding BeOneOf to ComparableTypeAssertions?

[dennisdoomen]

Indeed. We would welcome a PR.

[jez9999]

@dennisdoomen PR submitted.