Import `ShowBS` in `plutus-script-utils`

`cooked-validators` provides a `ShowBS` [module](https://github.com/tweag/cooked-validators/blob/main/src/Cooked/ShowBS.hs) which allows to print dynamic data within the execution of a script.

This is, of course, highly inefficient, but very useful outside of production code, for testing purpose. This would make more sense to have this module in PSU where the goal is to provide utilities for script building.