Add the ability to apply suppression flags for Core output

[tchoutri]

On user request, it would be interesting to provide a way to apply various suppression flags (https://downloads.haskell.org/ghc/latest/docs/users_guide/debugging.html#suppressing-unwanted-information) on the Core output

[tomsmeding]

I think this is #2 already, right?

[tchoutri]

ugh, yes absolutely

[s-and-witch]

@tchoutri you can use arbitrary options using OPTIONS_GHC pragma: https://play.haskell.org/saved/IMAPoEKI