This PR adds a https://github.com/casey/just
```
$ just
Available recipes:
build *opts # Build the project. `build runtime` builds only the runtime.
clean *opts # Clean the project. `clean runtime` cleans only the runtime. `clean juvix-build` cleans only juvix-build dirs.
format *opts # Formats all Haskell files in the project. `format changed` formats only changed files. `format FILES` formats individual files.
install # Install juvix
test *filter # Run the tests in the project. Use the filter arg to set a Tasty pattern.
```
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Co-authored-by: Jan Mas Rovira <janmasrovira@gmail.com>
