SPARQL ROUND() on xsd:doubles does not handle special values correctly

### Version

up to 5.6.0

### What happened?

e.g. 
* `ROUND("INF"^^xsd:double")` returns a numeric value.
* `ROUND("-0.1"^^xsd:double")` does not return negative zero.

The implementation relies on Java `Math.round(double)` which is not F&O compliant.


### Are you interested in making a pull request?

Yes