[FEATURE] The addAnchor setting is now valued

Checking the checkbox "Add link anchor" in a fluidcontent_core provided content element had no effect.

This change results in an `a` tag being rendered at the top of the content element.
Inline Fluid syntax can be broken into multiple lines as such:

```
<a id="{record.header -> v:or(alternative: record.titleAttribute)
    -> v:or(alternative: 'content {record.uid}') -> v:format.url.sanitizeString()}"></a>
```

It's not exactly pretty - 163 line length in a template is less problematic than in a PHP file so I'll accept this one. I think we have a few existing cases of lines this long or longer.