Smarter Dockerfile linter to validate best practices

Current versions

hadolint requires the following formulae to be installed:
ghc 8.2.1 Glorious Glasgow Haskell Compilation System
cabal-install Command-line interface for Cabal and Hackage

Formula history

ilovezfs Audit fixes for descriptions (#20013)
ilovezfs Use “squiggly” heredocs.
ilovezfs hadolint: depend on ghc (#16122)
ilovezfs hadolint: depend on ghc@8.0
ilovezfs hadolint 1.2.2
ilovezfs hadolint 1.2.1
Dominyk Tiller hadolint: call full path in test
lukasmartinelli hadolint 1.0 (new formula)