create a seperate config file for regex enhancers

@bastei can you check why phpunit gives me

```
1) OCA\News\Utility\ArticleEnhancer\XPathArticleEnhancerTest::testTransformRelativeUrlSpecials
OCA\News\Utility\ArticleEnhancer\XPathArticleEnhancer::substituteRelativeLinks(): unterminated entity reference             b=2

/srv/http/news/utility/articleenhancer/xpatharticleenhancer.php:125
/srv/http/news/utility/articleenhancer/xpatharticleenhancer.php:86
/srv/http/news/tests/unit/utility/articleenhancer/XPathArticleEnhancerTest.php:257


```

cc @icewind1991