Break lens dependency

[endgame]

Since amazonka and amazonka-* service bindings have all moved to using unprefixed records, Generic instances, and a strong recommendation to use one of generic-lens/generic-optics/-XOverloadedRecordDot, we should look at breaking the lens dependency in amazonka-2.1.

This means providing Van Laarhoven optics without depending on any particular optics package.

Most of this is pretty trivial, but we will have to degrade Amazonka.S3.Internal.keyComponents :: Delimiter -> IndexedTraversal' Int ObjectKey Text to keyComponents :: Delimeter -> Traversal' ObjectKey Text. Given that Control.Lens.Indexed.indexing exists, this is probably not too bad.