[DEVOPS-1061] Add support for cabal new-build

[rvl]

Description

Building with cabal new-build gives you a multi-package project with Nix downloading all of the dependencies from its binary cache.

Linked issue

https://iohk.myjetbrains.com/youtrack/issue/DEVOPS-1061

Type of change

• New feature in build system and dev environment.

Developer checklist

• Documentation updated accordingly.
• CHANGELOG entry has been added and is linked to the correct PR on GitHub.

QA Steps

nix-shell
cabal new-configure
cabal new-build all
cabal new-repl cardano-sl-wallet-new
stack --nix setup
stack --nix build
nix-build -A all-cardano-sl

[jmitchell]

NB: cabal new-configure failed for me when using an older version of cabal, but worked after upgrading (nix-env -f channel:nixos-18.09 -iA pkgs.cabal-install) and then updating the package cache by running cabal update.

This is already addressed in the PR with changes to docs/how-to/build-cardano-sl-and-daedalus-from-source-code.md.

Old version

$ cabal --version
cabal-install version 2.0.0.1
compiled using version 2.0.1.0 of the Cabal library

New version

$ cabal --version
cabal-install version 2.2.0.0
compiled using version 2.2.0.1 of the Cabal library

[michaelpj]

Randomly saw this, and thought I'd add (since I tried to get new-build working for the Plutus repo) that you want to filter out the GHC environment files in whatever you use to filter package source before building, otherwise things will randomly break mysteriously.