Pleroma federation2 (#1855)

Pleroma federation2 (#1855)

* Allow fetching person from Pleroma, including test case (ref #1461)

* Added test case for parsing community from apub json

- fixed a bug with objectid (de)serialization
- fixed a bug with outbox fetching (ref #1582)

* Added apub test for post

* Ignore errors when reading community outbox (fixes #1582)

* Dont fetch community outbox/moderators during tests

* added test for lemmy comment

* Added federation test for pleroma comment

* Added html2md crate to parse comment html from pleroma (fixes #1461)

* some fixes for update_apub_test_files.sh

* Add tests for ToApub, private message, remove update script

* Delete objects from db at the end of each test