Add authentication modules and configuration

[Stuart Clark]

Is your feature request related to a problem? Please describe.
As a user I want the ability to easily login to my site.

Describe the solution you'd like

• Add the Simple OAuth2 module to Drupal.
  • Configure as required in drupal-install command(?)
• Add the @nuxtjs/auth-next module to Nuxt.
  • Configure in nuxt.config.js
• Add support to synchronised OAUTH_CLIENT_ID environment variable

Describe alternatives you've considered

• password grant type would be a preferable login experience

Additional context

nuxt/auth-next config:

  auth: {
    redirect: {
      callback: '/callback',
      logout: '/',
    },
    strategies: {
      drupal: {
        scheme: 'oauth2',
        endpoints: {
          authorization: baseUrl + '/oauth/authorize',
          token: baseUrl + '/oauth/token',
          userInfo: baseUrl + '/oauth/userinfo',
        },
        clientId: process.env.OAUTH_CLIENT_ID,
        responseType: 'code',
        grantType: 'authorization_code',
        codeChallengeMethod: 'S256',
      },
    },
  },