[FEATURE] Allow headers to not be rendered on the frontend.

The headers are still visible in the backend. In CSSSC, the same effect would be achieved by setting a header to the "hidden" style. The header is still rendered in the backend and acts as a label on content elements.
afaik this can be flattened to 
```
{0: record.header, 1: '&&', 2: settings.header.hideHeader, 3: '!=', 4: 1}
```