Cardano Updates

   - Update Cabal 3.14 patch using https://github.com/stable-haskell/ghc/tree/stable-ghc-9.12
   - Restrict alex patch to versions before 9.12.3 (issue fixed upstream)
   - Add test suite for reinstallable GHC library (cabal and stack)
   - Tests verify GHC 9.12.2 and 9.12.3 can be reinstalled and linked against

Introduces a .small passthru variant on GHC derivations that opts out of
profiling libraries and Haddock documentation, significantly reducing closure
size for CI, Docker, and cross-compilation toolchain use cases.

Also fixes a pre-existing bug where `enableLibraryProfiling = false` had no
effect on Hadrian builds (GHC 9.4+): the `+no_profiled_libs` flavour
transformer was only applied for GHCJS/Wasm targets, silently ignoring the
parameter for all other platforms.

Changes:
- Add `enableHaddockDocs` parameter (default true, fully backwards-compatible)
- Fix legacy make build: HADDOCK_DOCS=NO now also honours enableHaddockDocs
- Fix Hadrian: +no_profiled_libs applied whenever enableLibraryProfiling=false
- Hadrian: --docs=nothing when enableHaddockDocs=false, no-sphinx otherwise
- Make sphinx and hscolour nativeBuildInputs conditional on enableHaddockDocs
- Add .small passthru variant (enableLibraryProfiling=false, enableHaddockDocs=false)

Usage: pkgs.haskell-nix.compiler.ghc967.small

Old versions of iogx pass `devShell` argument to `mkFlake` and it is not easy to upgrade to the latest `iogx` (since it has been significantly re-factored).

Supporting passing `devShell` should be harmless and it avoids forking iogx.

This fails to build `x` when it is needed because the string context is discarded when the `rawCabalProject` is parsed by haskell.nix.

This fix adds the context back so that the plan derivation will wind up depending on the `x`.

Old versions of iogx pass `devShell` argument to `mkFlake` and it is not easy to upgrade to the latest `iogx` (since it has been significantly re-factored).

Supporting passing `devShell` should be harmless and it avoids forking iogx.

This fails to build `x` when it is needed because the string context is discarded when the `rawCabalProject` is parsed by haskell.nix.

This fix adds the context back so that the plan derivation will wind up depending on the `x`.