Unify pretty-printing - Githubissues

First part of the code base unification effort (see Issue #13) This PR attempt to unify pretty-printing

terminology of SolcorePretty (ppr, pretty) is maintained
class Pretty moved to module Common.Pretty
engine switched to Text.PrettyPrint used so far by yule, because it outputs actual Solidity/Yul code and its behaviour should be kept.

rodrigogribeiro / solcore