Add yarn script commands for Drupal coding standard and Drupal Practice for Webtheme Default Content

Problem/Motivation

Drupal coding standard and Drupal Practice check should pass

PHPCS, PHPCBF for both --standard=Drupal and --standard=DrupalPractice

Check Webtheme Default Content Drupal coding standard

phpcbf --standard=Drupal --extensions=php,module,inc,install,test,theme,scss,css,info,txt,md,yml /var/www/html/products/webtheme_default_content/ --ignore=/var/www/html/products/webtheme_default_content/node_modules/

phpcs --standard=Drupal --extensions=php,module,inc,install,test,theme,scss,css,info,txt,md,yml /var/www/html/products/webtheme_default_content/ --ignore=/var/www/html/products/webtheme_default_content/node_modules/

Check Webtheme Default Content Drupal Practice

phpcbf --standard=DrupalPractice --extensions=php,module,inc,install,test,theme,scss,css,info,txt,md,yml /var/www/html/products/webtheme_default_content/ --ignore=/var/www/html/products/webtheme_default_content/node_modules/

phpcs --standard=DrupalPractice --extensions=php,module,inc,install,test,theme,scss,css,info,txt,md,yml /var/www/html/products/webtheme_default_content/ --ignore=/var/www/html/products/webtheme_default_content/node_modules/

Proposed resolution

yarn phpcs
yarn phpcbf
yarn lint:yaml

as

  "scripts": {
    "phpcs": "phpcs --standard=./.phpcs.xml .",
    "phpcbf": "phpcbf --standard=./.phpcs.xml .",
    "lint:yaml": "node ./node_modules/eslint/bin/eslint.js --config=.eslintrc.json --ext .yml ."
  },