xunit: define codefixes for SetAsserts

[Meir017]

The asserts defined in https://github.com/xunit/assert.xunit/blob/main/SetAsserts.cs

• [x] Contains<T>(T expected, ISet<T> set) #234
• [x] Contains<T>(T expected, IReadOnlySet<T> set) #234
• [x] Contains<T>(T expected, HashSet<T> set) #234
• [x] Contains<T>(T expected, ImmutableHashSet<T> set) #234
• [x] DoesNotContains<T>(T expected, ISet<T> set) #235
• [x] DoesNotContains<T>(T expected, IReadOnlySet<T> set) #235
• [x] DoesNotContains<T>(T expected, HashSet<T> set) #235
• [x] DoesNotContains<T>(T expected, ImmutableHashSet<T> set) #235
• [ ] ProperSubset<T>(ISet<T> expectedSubset, ISet<T>? actual)
• [ ] ProperSuperset<T>(ISet<T> expectedSubset, ISet<T>? actual)
• [x] Subset<T>(ISet<T> expectedSubset, ISet<T>? actual) #236
• [ ] Superset<T>(ISet<T> expectedSubset, ISet<T>? actual)

[Meir017]

• [ ] ProperSubset(ISet expectedSubset, ISet? actual)
• [ ] ProperSuperset(ISet expectedSubset, ISet? actual) related https://github.com/fluentassertions/fluentassertions/issues/2363