Support SatisfyRespectively for string collections

[jnyrup]

By moving SatisfyRespectively from GenericCollectionAssertions to SelfReferencingCollectionAssertions we enable string collections to re-use the same assertions.

To the best of my knowledge, this should not be a breaking change.

• Moving members to parent class is not a breaking change

• The return type has changed from AndConstraint<GenericCollectionAssertions<T>> to AndConstraint<TAssertions>, but for GenericCollectionAssertions<T> TAssertions is exactly GenericCollectionAssertions<T>.

This fixes #1188

[dennisdoomen]

• The return type has changed from AndConstraint<GenericCollectionAssertions<T>> to AndConstraint<TAssertions>, but for GenericCollectionAssertions<T> TAssertions is exactly GenericCollectionAssertions<T>.

Isn't changing the return type always a breaking change?

[jnyrup]

Hmm... You're probably right.
I'll change it to have be in both GenericCollectionAssertions<T> and StringCollectionAssertions for now.
Can consolidate it in 6.0

[jnyrup]

Pulling SatisfyRespectively up into SelfReferencingCollectionAssertions is not a breaking change.
Asked on SO and got an answer from Eric Lippert himself.
https://stackoverflow.com/questions/59255869/is-pulling-up-a-method-into-a-generic-base-class-a-breaking-change#comment104785181_59257698

[jnyrup]

The return type of GenericCollectionAssertions<T>.SatisfyRespectively does not change as:

• SelfReferencingCollectionAssertions<T, TAssertions>.SatisfyRespectively returns AndConstraint<TAssertions>
• GenericCollectionAssertions<T> derives from SelfReferencingCollectionAssertions<T, GenericCollectionAssertions<T>>
• So GenericCollectionAssertions<T>.SatisfyRespectively will still return AndConstraint<GenericCollectionAssertions<T>>

I asked the question on SO and got an answer from Eric Lippert himself.
https://stackoverflow.com/questions/59255869/is-pulling-up-a-method-into-a-generic-base-class-a-breaking-change/59257698#59257698