feat: add jobs option

[mrexox]

Closes #132

⚡ Summary

• Add jobs and group new options, so recursive piped/parallel flows could be built
• Implement the same run logic for jobs as for commands and scripts
• Properly merge jobs options with lefthook-local.yml and extends
• Add unit tests
• Add integration tests
• Add docs

Old syntax

pre-commit:
  parallel: true
  commands:
    lint:
      run: yarn lint
      stage_fixed: true
    fix-typos:
      run: typos
    migrate:
      run: lefthook run migrate
  scripts:
    "graphql-generate.sh":
      runner: bash

migrate:
  piped: true
  commands:
    setup:
      run: yarn setup
      priority: 1
    migrate:
      run: yarn migrate
      priority: 2

New syntax

pre-commit:
  parallel: true
  jobs:
    - name: lint
      run: yarn lint
      stage_fixed: true
    - run: typos
    - script: graphql-generate.sh
      runner: bash
    - name: migrate 
      group:
        piped: true
        jobs:
          - run: yarn setup
          - run: yarn migrate

[VanTanev]

Hey, a question here: Re do[].group.do[] items the same as do[] items?

In this case, the nested items don't have a name - is it valid for the top level items to also omit a name, and what happens then, is the name just the value of run?

btw I think this new config format is pretty neat.

[mrexox]

Yes, name is optional. The only mandatory options are either run, script, or group. run or script value will be used if name is empty, and for a group without a name it will be the index of a group - [3]