Deprecate methods using EncoderRegistry from DataConversion

The DataConversion carries an instance of EncodingRegistry, and exports operations that use it internally:

• isConversionSupported(MediaType mediaType)
• convert(Object o, MediaType from, MediaType to)
• convertToRequestFormat(Object o, MediaType contentType)

Those operations should be removed and moved to the EncoderRegistry itself, freeing the DataConversion objects from maintaining an internal reference to the registry. This also solves the issue of static DataContainer objects being used in mulitple nodes in the same JVM