Add sponsorship mrf

lib/pleroma/web/activity_pub/mrf/remove_sponsorship.ex

@@ -0,0 +1,24 @@
+defmodule Site.RemoveSponsorship do
+  @behaviour Pleroma.Web.ActivityPub.MRF
+
+  @impl true
+  def filter(
+        %{
+          "type" => "Create",
+          "object" => %{"content" => content, "attachment" => _} = _child_object
+        } = object
+      ) do
+    nc =
+      content
+      |> String.replace(~r/(<p>=&gt;|ufgloves).*/, "")
+      |> String.replace(~r/<p>--<br \/>Original: <a href="https:\/\/www\.twitter\.com\/.*/, "")
+
+    {:ok, put_in(object, ["object", "content"], nc)}
+  end
+
+  @impl true
+  def filter(object), do: {:ok, object}
+
+  @impl true
+  def describe, do: {:ok, %{}}
+end