Add pre-commit config

[homebysix]

This PR adds a pre-commit configuration, which can be used to automatically ensure AutoPkg recipes in this repo meet certain standards before git commit is executed.

In order to start using pre-commit, install it if you don't already have it (brew install pre-commit) and then cd to your recipe repo and run pre-commit install to activate the hooks.

For details on using pre-commit with AutoPkg, see this post: https://www.elliotjordan.com/posts/pre-commit-02-autopkg/

% pre-commit run --all-files
Check AutoPkg Recipes....................................................Passed
Forbid AutoPkg Overrides.................................................Passed
Forbid AutoPkg Trust Info................................................Passed