Merge branch 'auth-improvements' into 'develop'

Cookie auth rework / Auth subsystem refactoring and tweaks

Closes pleroma/secteam/pleroma#3

See merge request pleroma/pleroma!3112

test/pleroma/user_test.exs

@@ -2176,4 +2176,9 @@ defmodule Pleroma.UserTest do
 
     assert User.avatar_url(user, no_default: true) == nil
   end
+
+  test "get_host/1" do
+    user = insert(:user, ap_id: "https://lain.com/users/lain", nickname: "lain")
+    assert User.get_host(user) == "lain.com"
+  end
 end