Retire adapters.

It was proposed we break up the adapters to solve the dependency problem, but I wasn't motivated to perform the labor since I wasn't using any of these. Nobody stepped up to the plate, and we are starting to get dependency warnings, so I propose we retire this repo unless someone wants to step up to the plate and own these (or a subset of these).

Review the repository's adapters and the dependency warnings described in the issue. Determine whether the repository should be retired or whether specific adapters can be owned and maintained; completion depends on an explicit ownership or retirement decision.

Written by the indexing model from the issue text.