New hooks for packer fmt, fix and validate. Includes test files.

- Remove the Ansible Vault check hook, it did just the opposite. In case
  it's needed, use the one from
https://git.shore.co.il/ansible/ansible-pre-commit, any tag before
0.8.0.
- Remove the pip-outdated hook, it's a bad replacement for piprot (which
  is abandoned). If it's still needed use
https://git.shore.co.il/nimrod/python-pre-commit.

- A bunch of hooks, some copied from previous repos, some improvements
  on previous attempts, some new.
- README, CI, etc.
- A Python utilities module for helping with Python hooks.