[Python] Write serialized object as a stream of encapsulated IPC messages

[asfimport]

The structure of the stream in arrow::py::WriteSerializedObject is generated on an ad hoc basis – the components of the stream would be easier to manipulate if this were internally a generic stream of IPC messages. For example, one would be able to examine only the union that represents the structure of the serialized payload and leave the tensors undisturbed

Reporter: Wes McKinney / @wesm

Related issues:

• [Python] Convert SerializedPyObject to/from sequence of component buffers with minimal memory allocation / copying (is related to)
• [Python] Deprecate pyarrow serialization (is superceded by)

_{Note: This issue was originally created as ARROW-1509. Please see the migration documentation for further details.}

[asfimport]

Antoine Pitrou / @pitrou:
Not sure we still want to enhance the Python object serialization layer.