We currently have 2 sets of SSL configuration code, one in x-pack/plugin/core and another in libs/ssl-config

They do mostly the same thing and have a lot of code overlap, but for historical reasons they are separate.

It would be good to be able to drop the x-pack version and only have the libs/ version.

This has the risk of being a breaking change - it doesn't have to be, and we don't want it to be, but it's hard to be confident that there's zero impact - so we'd like to target a major release for it.