Add hlint configuration?

[philderbeast]

Linting was clean with #51 but now there are warnings:

# Warnings currently triggered by your code
- ignore: {name: "Empty single-line comment"} # 49 hints
- ignore: {name: "Redundant bracket"} # 4 hints
- ignore: {name: "Use intercalate"} # 10 hints
- ignore: {name: "Use map once"} # 4 hints
- ignore: {name: "Use zipWith"} # 1 hint

How about adding configuration (and a gh-action?) to help maintain this project in a lint-clean state?

I've seen the no-pull request note. If you want to pick up the configuration, I've done it over on typechecker@b42073e. The command for creating a default configuration is:

hlint --default -j . > .hlint.yaml