Refactor JSON templates to be generated with ActiveModelSerializers instead of Rabl (#4090)

app/presenters/status_relationships_presenter.rb

@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+class StatusRelationshipsPresenter
+  attr_reader :reblogs_map, :favourites_map, :mutes_map
+
+  def initialize(statuses, current_account_id = nil)
+    if current_account_id.nil?
+      @reblogs_map    = {}
+      @favourites_map = {}
+      @mutes_map      = {}
+    else
+      status_ids       = statuses.compact.flat_map { |s| [s.id, s.reblog_of_id] }.uniq
+      conversation_ids = statuses.compact.map(&:conversation_id).compact.uniq
+      @reblogs_map     = Status.reblogs_map(status_ids, current_account_id)
+      @favourites_map  = Status.favourites_map(status_ids, current_account_id)
+      @mutes_map       = Status.mutes_map(conversation_ids, current_account_id)
+    end
+  end
+end