Export all internal functions in Distribution.Simple.Utils in .Internal module

[nh2]

Trying to work around #5756 in my Cabal hook, I can't easily make a

noticeSay :: Verbosity -> Text -> IO ()

using say because lots of functions used inside notice aren't exported.

Now I have to copy-paste many functions from that module in order to do it; this is wasting a lot of time to get simple things done.

Cabal should export all the useful functions that aren't public API in an .Internal module, so that people can use that to work around problems until things get fixed upstream.

[23Skidoo]

Fine. Do you need this in the 2.4 branch?