Add Codeception tool

[tormi]

There is currently a lando codeception tool defined in .lando.yml, but it has never worked because there's no codeception package added to composer.json:

tooling:
  codeception:
    service: appserver
    description: Run codeception
    cmd:
      - ./vendor/bin/codecept
      - "--env=lando"

Let's add either codeception/codeception or guncha25/drupal-codeception package + testing setup.

See also:

• Fix codeception acceptance tests #37
• 6240c75

cc: @guncha25 , @floretan

[tormi]

I've removed non-functional lando codecept tool for now here: 9bf67d5

[tormi]

Readme:

• lando codecept <commands> - run codeception tests.

Tool definition:

  codecept:
    description: Runs codeception tests
    cmd:
      - appserver: ./vendor/bin/codecept

[tormi]

Our internal guide which needs to be implemented here: https://intra.wunder.io/info/documentation-and-best-practices/drupal-project-testing-setup