Investigate current python modules for ActivityPub integration

[ahouseholder]

Research and evaluate extant python modules that do activitypub things.

• PyFed https://dev.funkwhale.audio/funkwhale/pyfed (note that there is another pyfed that appears to have nothing to do with ActivityPub)

was the one that originally got my attention, but there are many matches at https://pypi.org/search/?q=activitypub
like

• https://pypi.org/project/activitypubdantic/
• https://pypi.org/project/minimal-activitypub/

and others

• https://github.com/dsblank/activitypub
• https://github.com/tOkeshu/activitypub-example
• https://github.com/dariusk/express-activitypub
• https://github.com/rowanlupton/pylodon

We're going to need to look at a few of these and see if anything fits our needs (which are still somewhat nebulous, so this is an exploratory issue).