[WIP] Applied CCA-CodeStyle and CCA-Build-System

I've fixed a few last CS errors. But I have a problem with author-validation again:
@discordier could you have a fast look on it?

```
author-validation:
[author-validation] The file /Applications/MAMP/htdocs/metamodels/contao-extensions/metamodels-attribute_tags/src/MetaModels/Attribute/Tags/MetaModelTags.php is not mentioning its author(s):
[author-validation] Christopher Boelter <christopher@boelter.eu>
[author-validation] The file /Applications/MAMP/htdocs/metamodels/contao-extensions/metamodels-attribute_tags/src/MetaModels/DcGeneral/Events/Table/Attribute/Tags/Subscriber.php is not mentioning its author(s):
[author-validation] Christopher Boelter <christopher@boelter.eu>
```