overloaded `toContain` for Set

[robstoll]

We currently share the logic for all Iterable when it comes to toContain. However, we could provide a faster implementation for contains values because there will never be more than 1 value in a Set and thus it does not make sense to list how many occurrences we found. The same does not apply to the overload expecting one or multiple assertionCreator (Expect<E>.() -> Unit). Hence:

• overload value(e: E) and values(e: E, vararg otherE: E) for Expect<T: Set<E>>
• overload toContain(E) for Expect<T: Set<E>>

[JithendraD]

hey @robstoll, can I work on this

[robstoll]

@JithendraD This is certainly not an easy task to start with and I recommend you start with a good first issue first. But you can give it a go if you like