This is based on #1159 , which should be reviewed first. (The only dependency between the two is in the mocks)

This deprecates the current methods in RDF4JBodyHandlers, and replaces them with similar method throwing an appropriate exception with error details on HTTP error instead of returning an empty dataset. This makes use of the composable throwing body handler now exposed by the Response interface of the api module. The new method now have RDF4J in their name for this not to be a breaking change: ofModel becomes ofRDF4JModel, etc.