Implement MutatorTuple for Vecs to allow Dynamic Mutator Choices

[domenukk]

This PR adds a .into_vec function to MutatorsTuple and makes Vec<Box<dyn Mutator<I, S>>> implement MutatorsTuple - allowing us to use vecs instead of proper tuples in certain places.

[addisoncrump]

I really don't think this is the right answer. A Vec of mutators of a common type would be more appropriate, or using Tuneable. Introducing dyn makes future design decisions more restrictive and less user-friendly in the end.

[domenukk]

As long as you don't use dyn you don't have any downsides, right?

[addisoncrump]

We've talked about this offline and I think we came to the conclusion that having dyn around but explicitly documenting it as not preferred (not deprecating the functionality) is a reasonable middle ground.