Provide cabal-cache executable

[patrickt]

Using cabal-cache appears to yield superior results in Cabal-using projects that would otherwise have to simulate a cache by preserving the Cabal store and the dist-newstyle build results. We should provide it natively.

[larskuhtz]

You may take a look at https://github.com/larskuhtz/cabal-cache-action , which I haven't yet officially released, but which works fine for me in production.