Initial bundle of basic AdminFE

Due to CSP headers we only allow connecting to self. If you want to
host AdminFE on a separate domain without CSP headers you will be able
to connect to any public Pleroma host.

lib/pleroma/web/endpoint.ex

@@ -29,6 +29,13 @@ defmodule Pleroma.Web.Endpoint do
     # credo:disable-for-previous-line Credo.Check.Readability.MaxLineLength
   )
 
+  plug(Plug.Static.IndexHtml, at: "/pleroma/admin/")
+
+  plug(Plug.Static,
+    at: "/pleroma/admin/",
+    from: {:pleroma, "priv/static/adminfe/"}
+  )
+
   # Code reloading can be explicitly enabled under the
   # :code_reloader configuration of your endpoint.
   if code_reloading? do