Add extra convenience method #toUrlForm to HstLink

Only current available method is org.hippoecm.hst.core.linking.HstLink#toUrlForm(HstRequestContext, boolean). I think that the number of times you want a fully qualified URL (and thus set the boolean to true) is very low (for REST output for example). Now you must always set that and think about that.

A HstLink#toUrlForm() would be a nice addition, which by default would give relative URLs. Can the HstRequestContext parameter also go? The code internally can get it easily with

RequestContextProvider.get(). No need to pass it to the method.