Leveling Up - First cabal test suite

file to edit: https://github.com/haskell/cabal-userguide/blob/main/src/leveling_up/02_first_cabal_test-suite.md

## Brief Summary

The motivation for this chapter is to show users how to setup a test suite in cabal, how to test their library, and how to test their executable code. It would be helpful to mention how compilation works wrt test suites.

## Resources

[Old cabal user guide test reference](https://cabal.readthedocs.io/en/3.4/cabal-package.html#test-suites)