Allow hook commands to be reused

[laura-turner-evolvemep]

⚡ Summary

It would be useful to reuse a hook command across multiple hooks. For example, using the same command across both post-checkout and post-merge.

Value

Some hooks need to run the same commands; copy and pasting these commands is more error prone, especially if these commands need to be changed in the future.

Behavior and configuration changes

A way I've though of changing this is to be able to define a top-level commands map in lefthook.yml, and then be able to reference it in my hooks. For example:

Current config (simplified)

post-merge:
  commands:
    install-packages:
      run: yarn

post-checkout:
  commands:
    install-packages:
      run: yarn

Updated config

post-merge:
  commands:
    install-packages

post-checkout:
  commands:
    install-packages

commands:
  install-packages:
    run: yarn