Add support for funkwhale Audio activity

reel2bits fixture not included as it lacks the Actor fixture for it.

Closes: https://git.pleroma.social/pleroma/pleroma/issues/1624
Closes: https://git.pleroma.social/pleroma/pleroma/issues/764

test/web/oauth/oauth_controller_test.exs

@@ -581,7 +581,7 @@ defmodule Pleroma.Web.OAuth.OAuthControllerTest do
       # In case scope param is missing, expecting _all_ app-supported scopes to be granted
       for user <- [non_admin, admin],
           {requested_scopes, expected_scopes} <-
-            %{scopes_subset => scopes_subset, nil => app_scopes} do
+            %{scopes_subset => scopes_subset, nil: app_scopes} do
         conn =
           post(
             build_conn(),