New tool request: add ormolu into the toolchain

[evan0greenup]

ormolu is a popular Haskell formatter for developers. It would be nice to provide a static compiled ormolu in ghcup toolchain.

stack install ormolu is difficult to clean and do version management. This tool is pretty feature-completed.

[hasufell]

GHCup generally is about installing the Haskell toolchain, which is defined as:

• GHC
• cabal-install
• HLS
• stack

Right now there are no plans to extend this to other arbitrary binaries, although there was a design discussion about being able to install arbitrary binaries: haskell/ghcup-hs#141

I've considered adding cabal-cache to ghcup simply because it's hard to bootstrap it yourself and compiling it from source defeats the purpose of it speeding up CI times. I have low appetite for formatters though. If we ever manage to come up with said installed DLS, someone else may be able to provide ormolu binaries.