This new 'PackageType' addresses the common use case of getting a package set up
as quickly as possible without needing to go through the full interactive
prompt. We move the 'getLibOrExec' prompt to the front of the list, and if
'SimpleProject' is selected we bypass the rest of the interactive prompt and use
the defaults.

This behaviour can also be invoked via: cabal init --simple

Testing:
- Manually tested