Library of process-compose functions

[shlevy]

In my own project, I’m setting up a process-compose that basically matches run-process-compose-dbsync-foo exported by this flake, but pointed at a local ephemeral testnet. Currently I’m planning to just copy-paste a bunch out of process-compose/default.nix, but would be nice if there were a clean library interface that was used both by cardano-parts and exposed to external users.