Add support for codeception .dist.yml

[DanielSiepmann]

Extend detection for codeception test file.
Respect codeception.dist.yml beside codeception.yml.

As documented by https://codeception.com/docs/reference/Configuration#Configuration-Templates-distyml

Make sure these boxes are checked before submitting your pull request:

• Add fixtures and spec when implementing or updating a test runner
• Update the README accordingly
• Update the Vim documentation in doc/test.txt

[DanielSiepmann]

I don't know how to extend https://github.com/vim-test/vim-test/blob/master/spec/codeception_spec.vim as I guess we would need to change the structure of https://github.com/vim-test/vim-test/tree/master/spec/fixtures/codeception ?
How would you like me to adapt tests, add another spec.vim which uses a different fixture folder?

[codeinabox]

I don't know how to extend https://github.com/vim-test/vim-test/blob/master/spec/codeception_spec.vim as I guess we would need to change the structure of https://github.com/vim-test/vim-test/tree/master/spec/fixtures/codeception ? How would you like me to adapt tests, add another spec.vim which uses a different fixture folder?

Thank you for this! As for the spec I'd do something like this:

  it "also recognizes codeception.dist.yml"
    try
      !mv codeception.yml codeception.dist.yml
      view tests/functional/NormalCest.php
      TestSuite

      Expect g:test#last_command == 'codecept run'
    finally
      !mv codeception.dist.yml codeception.yml
    endtry
  end

[codeinabox]

Thank you for taking the time to add a test, very much appreciated