* Move ActivityPub::FetchRemoteAccountService to ActivityPub::FetchRemoteActorService

ActivityPub::FetchRemoteAccountService is kept as a wrapper for when the actor is
specifically required to be an Account

* Refactor SignatureVerification to allow non-Account actors

* fixup! Move ActivityPub::FetchRemoteAccountService to ActivityPub::FetchRemoteActorService

* Refactor ActivityPub::FetchRemoteKeyService to potentially return non-Account actors

* Refactor inbound ActivityPub payload processing to accept non-Account actors

* Refactor inbound ActivityPub processing to accept activities relayed through non-Account

* Refactor how Account key URIs are built

* Refactor Request and drop unused key_id_format parameter

* Rename ActivityPub::Dereferencer `signature_account` to `signature_actor`

* Change relays handling to not record boosts

* Update tests

* Add support for inlined objects in activity audience

* Add tests

* Do not misattribute inlined boosts if `attributedTo` isn't present

Fixes #10950

* Fix tests

* Fix reblogs privacy

* Fix Announce processing specs

Regression from #9998

* Filter incoming Announce activities by relation to local activity

Reject if announcer is not followed by local accounts, and is not
from an enabled relay, and the object is not a local status

Follow-up to #10005

* Fix tests

* When self-boosting, embed original toot into Announce serialization

* Process unknown self-boosts from Announce object if it is more than an URI

* Add some self-boost specs

* Only serialize private toots in self-Announces

* 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