FEATURE: Make allow_uploaded_avatars accept TL (#14091)

This gives admins more control over who can upload custom profile
pictures.

db/migrate/20210819152920_change_allow_uploaded_avatars.rb

@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+class ChangeAllowUploadedAvatars < ActiveRecord::Migration[6.1]
+  def up
+    execute <<~SQL
+      UPDATE site_settings
+      SET data_type = 7, value = (CASE WHEN value = 'f' THEN 'disabled' ELSE '0' END)
+      WHERE name = 'allow_uploaded_avatars'
+    SQL
+  end
+
+  def down
+    execute <<~SQL
+      UPDATE site_settings
+      SET data_type = 5, value = (CASE WHEN value = 'disabled' THEN 'f' ELSE 't' END)
+      WHERE name = 'allow_uploaded_avatars'
+    SQL
+  end
+end