* all-cabal-hahses can be a directory
Motivating problem: we want to use the flake.lock for all-cabal-hashes
as a github repository as our revision pin, and then import that to pass
as all-cabal-hashes. To do that we need it to accept a directory rather
than a tarball.
* all-cabal-hashes: add some comments
f28ab51b54