[feature] Federate pinned posts (aka featuredCollection) in and out (#1560)

* start fiddling

* the ol' fiddle + update

* start working on fetching statuses

* poopy doopy doo where r u uwu

* further adventures in featuring statuses

* finishing up

* fmt

* simply status unpin loop

* move empty featured check back to caller function

* remove unnecessary log.WithContext calls

* remove unnecessary IsIRI() checks

* add explanatory comment about status URIs

* change log level to error

* better test names

internal/api/activitypub/users/user.go

@@ -50,6 +50,8 @@ const (
 	FollowersPath = BasePath + "/" + uris.FollowersPath
 	// FollowingPath is for serving GET request's to a user's following list, with the given username key.
 	FollowingPath = BasePath + "/" + uris.FollowingPath
+	// FeaturedCollectionPath is for serving GET requests to a user's list of featured (pinned) statuses.
+	FeaturedCollectionPath = BasePath + "/" + uris.CollectionsPath + "/" + uris.FeaturedPath
 	// StatusPath is for serving GET requests to a particular status by a user, with the given username key and status ID
 	StatusPath = BasePath + "/" + uris.StatusesPath + "/:" + StatusIDKey
 	// StatusRepliesPath is for serving the replies collection of a status.
@@ -71,6 +73,7 @@ func (m *Module) Route(attachHandler func(method string, path string, f ...gin.H
 	attachHandler(http.MethodPost, InboxPath, m.InboxPOSTHandler)
 	attachHandler(http.MethodGet, FollowersPath, m.FollowersGETHandler)
 	attachHandler(http.MethodGet, FollowingPath, m.FollowingGETHandler)
+	attachHandler(http.MethodGet, FeaturedCollectionPath, m.FeaturedCollectionGETHandler)
 	attachHandler(http.MethodGet, StatusPath, m.StatusGETHandler)
 	attachHandler(http.MethodGet, StatusRepliesPath, m.StatusRepliesGETHandler)
 	attachHandler(http.MethodGet, OutboxPath, m.OutboxGETHandler)