Assumes that the dir exists The function creates the salt if it does not exist, or it returns the existing salt if it's already there.

TODO: refactor/tidy extendInputs is only relevant for the "input step".

Global vs Mod salt behaviour: - We should only create the salt *automatically* in the "global" location: `~/.flowpipe/internal/salt ` - A user may create a "mod salt" file in the mod manually (`./.flowpipe/internal/salt`) - If there is a mod salt, it is used for triggers, otherwise use the global salt.