Add OpenAPI spec for CustomEmojiController

lib/pleroma/web/mastodon_api/controllers/custom_emoji_controller.ex

@@ -5,6 +5,10 @@
 defmodule Pleroma.Web.MastodonAPI.CustomEmojiController do
   use Pleroma.Web, :controller
 
+  plug(OpenApiSpex.Plug.CastAndValidate)
+
+  defdelegate open_api_operation(action), to: Pleroma.Web.ApiSpec.CustomEmojiOperation
+
   def index(conn, _params) do
     render(conn, "index.json", custom_emojis: Pleroma.Emoji.get_all())
   end