feat(spin): create spin wrapper given data format name

related to CAM-3021
chore(doc): update 'extending Spin' section

- removes documentation of old configuration API

related to CAM-2966
chore(xml): JaxBContextProvider returns Marshaller and Unmarshaller

- should not directly return JaxBContext, as then there is no possibility
  to configure marshallers and unmarshallers (e.g. setting XML schemas on
  these for validation

related to CAM-3021
chore(spin): remove XML(Object, DataFormat), JSON(Object, DataFormat)

- these API methods are not required as S(Object, DataFormat) is equally
  powerful

related to CAM-3021