Make Hadrian build with Cabal-3.2

GHC 8.10 ships with Cabal-3.2.0.0, so it would be convenient to make Hadrian supporting building against 3.2.* instead of having to rebuild the entirety of Cabal-3.0.0.0. There is one API change in Cabal-3.2.* that affects Hadrian: the synopsis and description functions now return ShortText instead of String. Since Hadrian manipulates these Strings in various places, I found that the simplest fix was to use CPP to convert ShortText to Strings where appropriate.