Enable Hoogle for local packages

[sellout]

It rebuilds GHC, but is worth it to have a Hoogle server.

[aryairani]

sgtm

[ceedubs]

I'm someone who builds this project a lot to use a recent unison build but rarely does development on the unison codebase itself. So I never use the local hoogle and find the lengthy build of ghc from source to be pretty annoying when my direnv loads this devShell. Hopefully I can build it and it doesn't change often so it's not a big deal. But I also wonder if it might make sense to have a version of the shell that doesn't include it? At the same time I'm hesitant to add further logic to the already lengthy nix config in this repo :D

[sellout]

So I never use the local hoogle and find the lengthy build of ghc from source to be pretty annoying when my direnv loads this devShell. Hopefully I can build it and it doesn't change often so it's not a big deal.

You should never have to build this. It’s in draft because it’ll require manually pushing the builds to Cachix before it can be merged. After which, no one should have to build it again.

I know that hasn’t always worked properly, but if you find yourself ever building GHC (without having mucked with the flake inputs or something), that’s a bug.