* feat(models): a quickie lil update
- adds fave and comment count
(mutations to come)
- adds source app to commit within stream query
* feat(client): add favorite mutation
* feat(models): `ActivityCollection` and `Activity`
* feat(client): stream activity method
* test(client): test for stream activity
* refactor(client): use datetime args for activity
* docs(client): clean up stream activity docstring
* feat/test(client): user activity
izzy lyseggen