support using lintstaged for hooks

[xenoterracide]

although I can add the precommit instructions to our .huskyrc I'd really like to just be able to run ./gradlew ktlintFormat in my lintstagedrc. https://github.com/okonet/lint-staged yes I know this is a node tool, but we're using prettier for formatting a lot of things that aren't kotlin, as well as a few other hooks. It does most of the work done in the hook for you. It's possible this is already possible just not documented.