Update stylish-haskell to use ghc-lib-parser

Stylish-haskell is a code prettifier that formats Haskell programs relying on the haskell-src-exts library to parse the Haskell code into an AST. Since this library is not actively maintained it needs to be replaced with another library that allows to keep up with the de-facto standard compiler: GHC. The parsing library ghc-lib-parser packages the parser from GHC itself, and as such, is always up to date. The project mainly aims to do the port to ghc-lib-parser, eventually also introducing improvements. The project will guarantee the continuity of the package stylish-haskell, allowing users to keep benefit from it.