docs: not clear that generated types have serialize / deserialize methods

[tswast]

I had a customer that was pickling protobuf objects because they didn't know they could serialize / deserialize the protocol buffer objects. (internal issue 171748167)

If you browse the documentation at https://googleapis.dev/python/bigquerystorage/latest/bigquery_storage_v1/types.html there is no indication that this is possible.

Suggestion 1

Show that these objects are inherited from proto-plus message objects and use intersphinx to ensure they get a clickable link to the Message reference docs https://proto-plus-python.readthedocs.io/en/latest/reference/message.html#proto.message.Message

Suggestion 2

Add :show-inheritance: and :inherited-members: to the types.rst file.

[tswast]

Possibly fixed by #680 ? Looks like I haven't merged that change into bigquery-storage yet.

[software-dov]

What's the consensus on whether this is fixed by #680 ?

[tswast]

I haven't cut a release yet since googleapis/python-bigquery-storage#91 and googleapis/python-bigquery-storage#86 so I'm not sure if it's enough. Should be an improvement at least, though.

[software-dov]

Moving to close since the change has been made in the generator.

[tswast]

Thanks, just cut a release. https://googleapis.dev/python/bigquerystorage/latest/bigquery_storage_v1/types.html looks pretty good to me. Hopefully customers click on that base class link.