Print where kernel is installed

improve flake by distinguishing different goals (development vs final executable vs with a jupyter environment)

we used to expose just the ihaskellEnv. Also added devShell and attribute set for 921. I've renamed some of the packages on the same model as haskell-language-server.

IHaskellPrelude imports most of it

Remove imports

to make the buildlogs clearer

to fix build issues

Handle plugin initialization using :set -fplugin module

Handle plugin initialization using :set -fplugin .. Previously plugins were (almost) silently ignored

For jupyter

flake.nix now:
- expose an overlay to be used by for instance jupyterWith
- disabled tests 'cos failing
- bring haskell-language-server though it seems to choke on codebase

* .github/workflows/nix.yml: build release-{9.0,9.2}.nix as well

* release-9.2.nix: update

* Fix more hash mismatches

* release-9.2.nix: update

* .github/workflows/nix.yml: don't test for release-9.2.nix

* .github/workflows/nix.yml: fix comment indentation

build: add flake support