[Feature Request] Specify string comparison for `string.Contain()` and friends

Please consider adding support to specify string comparison options, to: Contain(), ContainAll(), ContainAny(), NotContain(), NotContainAll(), NotContainAny().

Then instead of this:

foo.ToUpperInvariant().Should().NotContainAny(
  nameof(Foo.Spam).ToUpperInvariant(),
  nameof(Foo.Ham).ToUpperInvariant(),
  nameof(Foo.Eggs).ToUpperInvariant(),
  nameof(Something).ToUpperInvariant(),
  "bar".ToUpperInvariant()
);

We could do this:

foo.Should().NotContainAny(
  StringComparison.InvariantCultureIgnoreCase,
  nameof(Foo.Spam),
  nameof(Foo.Ham),
  nameof(Foo.Eggs),
  nameof(Something),
  "bar"
);

(Yes, I chose the ugliest example. I needed to make a point! 😄 Thanks.)

[lonix1]

Also a good point. In my experience, sometimes, when the problem seems too complicated the best option is to do nothing. Often it’s a problem that doesn’t require solving.

My code won’t explode if these overloads aren’t added. If it’s easier to ignore my feature request, please do so. And thanks for maintaining this awesome library.

[dennisdoomen]

ContainAllEquivalentOf -> ContainOnlyEquivalentOf