feat: add *.graphql support

[natterstefan]

Feature Request

Support using .graphql files in your project.

Basic example

/* eslint-disable global-require */
/**
 * @type {import('eslint').ESLint.Options}
 */
module.exports = {
  extends: [
    'eslint-config-ns-ts',
  ],
  plugins: ['graphql']
  overrides: [
    {
      files: ['*.graphql', '.gql'],
      rules: {
        /**
         * Graphql linting
         *
         * This plugin also lints GraphQL literal files ending on .gql or .graphql.
         * In order to do so set env to 'literal' to tell eslint to check these
         * files as well.
         */
        'graphql/template-strings': [
          'error',
          {
            env: 'apollo',
            schemaJson: require('./graphql/schema.json'),
          },
          {
            validators: [
              'FieldsOnCorrectTypeRule',
              'NoFragmentCyclesRule',
              'UniqueOperationNamesRule',
              'UniqueArgumentNamesRule',
            ],
            env: 'literal',
            schemaJson: require('./graphql/schema.json'),
          },
        ],
        'graphql/named-operations': [
          'error',
          {
            env: 'literal',
            schemaJson: require('./graphql/schema.json'),
          },
        ],
        'graphql/no-deprecated-fields': [
          'warn',
          {
            env: 'literal',
            schemaJson: require('./graphql/schema.json'),
          },
        ],
        // 'graphql/required-fields': [
        //   'error',
        //   {
        //     env: 'literal',
        //     schemaJson: require('./graphql/schema.json'),
        //     /**
        //      * ensure that we never miss adding `id` to queries, as this can
        //      * lead to nasty issues with apollo.
        //      */
        //     requiredFields: ['id'],
        //   },
        // ],
      },
    },
  ],
}

Tasks

• define how to provide schemaJson files (1 and multiple/different ones).
• add note that currently only @apollo/client code is tested

Notes

• use https://github.com/B2o5T/graphql-eslint instead of https://github.com/apollographql/eslint-plugin-graphql (see notes about Upcoming Deprecation Plans)
• example w/ apollo project: nodkz/example-apollo3@b885992...ecbc76b