* Prepare Mastodon for zeitwerk autoloader (Rails 6)

Add inflections and rename/move a few classes.

In particular, app/lib/exceptions.rb and app/lib/sanitize_config.rb
were manually loaded while still in autoload paths.

* Add inflection for Url → URL

* Fix "tootctl media remove-orphans" crashing on “Import” files

* Also remove empty directories when removing orphaned media

* Add nodeinfo endpoint

* dont commit stuff from my local dev

* consistant naming since we implimented 2.1 schema

* Add some additional node info stuff

* Add nodeinfo endpoint

* dont commit stuff from my local dev

* consistant naming since we implimented 2.1 schema

* expanding this to include federation info

* codeclimate feedback

* CC feedback

* using activeserializers seems like a good idea...

* get rid of draft 2.1 version

* Reimplement 2.1, also fix metaData -> metadata

* Fix metaData -> metadata here too

* Fix nodeinfo 2.1 tests

* Implement cache for monthly user aggregate

* Useless

* Remove ostatus from the list of supported protocols

* Fix nodeinfo's open_registration reading obsolete setting variable

* Only serialize domain blocks with user-facing limitations

* Do not needlessly list noop severity in nodeinfo

* Only serialize domain blocks info in nodeinfo when they are set to be displayed to everyone

* Enable caching for nodeinfo endpoints

* Fix rendering nodeinfo

* CodeClimate fixes

* Please CodeClimate

* Change InstancePresenter#active_user_count_months for clarity

* Refactor NodeInfoSerializer#metadata

* Remove nodeinfo 2.1 support as the schema doesn't exist

* Clean-up

* Add ActivityPub inbox

* Handle ActivityPub deletes

* Handle ActivityPub creates

* Handle ActivityPub announces

* Stubs for handling all activities that need to be handled

* Add ActivityPub actor resolving

* Handle conversation URI passing in ActivityPub

* Handle content language in ActivityPub

* Send accept header when fetching actor, handle JSON parse errors

* Test for ActivityPub::FetchRemoteAccountService

* Handle public key and icon/image when embedded/as array/as resolvable URI

* Implement ActivityPub::FetchRemoteStatusService

* Add stubs for more interactions

* Undo activities implemented

* Handle out of order activities

* Hook up ActivityPub to ResolveRemoteAccountService, handle
Update Account activities

* Add fragment IDs to all transient activity serializers

* Add tests and fixes

* Add stubs for missing tests

* Add more tests

* Add more tests

* Improve webfinger templates and make tests more flexible

* Clean up AS2 representation of actor

* Refactor outbox

* Create activities representation

* Add representations of followers/following collections, do not redirect /users/:username route if format is empty

* Remove unused translations

* ActivityPub endpoint for single statuses, add ActivityPub::TagManager for better
URL/URI generation

* Add ActivityPub::TagManager#to

* Represent all attachments as Document instead of Image/Video specifically
(Because for remote ones we may not know for sure)

Add mentions and hashtags representation to AP notes

* Add AP-resolvable hashtag URIs

* Use ActiveModelSerializers for ActivityPub

* Clean up unused translations

* Separate route for object and activity

* Adjust cc/to matrices

* Add to/cc to activities, ensure announce activity embeds target status and
not the wrapper status, add "id" to all collections

Rename Activitypub to ActivityPub