feature: Add remote config support

[mrexox]

Closes #155, #323

⚡ Summary

Remotes allow to share lefthook configurations without a need to maintain one lefthook.yml in all repos where you need it to be unique.

For example:

remotes:
  git_url: git@github.com:evilmartians/lefthook # Repo URL (https:// or git@)
  ref: v1.2.0                                   # Optional reference (tag or branch)
  config: examples/ruby-linters.yml             # Optional file path (default is lefthook.yml)

🍅 This PR tasks

• Support remote option
  • Support custom config name option
  • Support custom ref option for referencing branches or tags
• Sync or clone repo on lefthook install
• Merge with remote configuration
• Support scripts from remote
• Support extends from remote
• Add tests
• Provide some config examples
• Update docs

[mrexox]

Hey @oatovar! I am going to merge this PR into master. I have a few tasks to do before releasing v1.2.0, but remotes support will be the main feature I think.

If you have the desire and time, please, test this feature. I'll be glad to see some feedback. I marked this feature as beta, so we can change its behavior slightly in future releases.

[oatovar]

@mrexox Thank you so much for working on this feature! 🙇 I'll begin testing this out today and create any issues I come across.