feat(cli): implement print-config cli flag

[armano2]

Description

implement --print-config cli flag

fixes #858

Motivation and Context

Usage examples

$ commitlint --print-config --no-color

{
  extends: [
    './@commitlint/config-conventional',
    './@commitlint/config-lerna-scopes'
  ],
  formatter: '@commitlint/format',
  parserPreset: {
    name: 'conventional-changelog-conventionalcommits',
    path: './node_modules/conventional-changelog-conventionalcommits/index.js',
    parserOpts: {
      headerPattern: /^(\w*)(?:\((.*)\))?!?: (.*)$/,
      breakingHeaderPattern: /^(\w*)(?:\((.*)\))?!: (.*)$/,
      headerCorrespondence: [ 'type', 'scope', 'subject' ],
      noteKeywords: [ 'BREAKING CHANGE' ],
      revertPattern: /^(?:Revert|revert:)\s"?([\s\S]+?)"?\s*This reverts commit (\w*)\./i,
      revertCorrespondence: [ 'header', 'hash' ],
      issuePrefixes: [ '#' ]
    }
  },
  ignores: undefined,
  defaultIgnores: undefined,
  plugins: {},
  rules: {
    'body-leading-blank': [ 1, 'always' ],
    'body-max-line-length': [ 2, 'always', 100 ],
    'footer-leading-blank': [ 1, 'always' ],
    'footer-max-line-length': [ 2, 'always', 100 ],
    'header-max-length': [ 2, 'always', 100 ],
    'scope-case': [ 2, 'always', 'lower-case' ],
    'subject-case': [
      2,
      'never',
      [ 'sentence-case', 'start-case', 'pascal-case', 'upper-case' ]
    ],
    'subject-empty': [ 2, 'never' ],
    'subject-full-stop': [ 2, 'never', '.' ],
    'type-case': [ 2, 'always', 'lower-case' ],
    'type-empty': [ 2, 'never' ],
    'type-enum': [
      2,
      'always',
      [
        'build',  'chore',
        'ci',     'docs',
        'feat',   'fix',
        'perf',   'refactor',
        'revert', 'style',
        'test'
      ]
    ],
    'scope-enum': [
      2,
      'always',
      [
        'commitlint-config-angular',
        'commitlint-config-lerna-scopes',
        'commitlint-config-patternplate',
        'commitlint',
        'cli',
        'config-angular-type-enum',
        'config-angular',
        'config-conventional',
        'config-lerna-scopes',
        'config-patternplate',
        'core',
        'ensure',
        'execute-rule',
        'format',
        'is-ignored',
        'lint',
        'load',
        'message',
        'parse',
        'prompt-cli',
        'prompt',
        'read',
        'resolve-extends',
        'rules',
        'to-lines',
        'top-level',
        'travis-cli',
        'types',
        'babel-preset-commitlint',
        'test-environment',
        'test',
        'utils'
      ]
    ]
  },
  helpUrl: 'https://github.com/conventional-changelog/commitlint/#what-is-commitlint'
}

How Has This Been Tested?

unit tests + manual tests

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

[armano2]

I'm unsure if this is best way to get resolved config, should we include here configuration that comes from cli arguments?

i think load should not return extends

[escapedcat]

should we include here configuration that comes from cli arguments?

I think that would be nice to always reflect the actual used configuration.

i think load should not return extends

@byCedric ?

[armano2]

I think that would be nice to always reflect the actual used configuration.

ok, than its correct

[escapedcat]

Thanks! ❤️