Remove menu entry option types because this page is not really usable

We keep the underlying data structures because option types and option values are used internally to keep units in OFN: weight, volume and items, but otherwise, custom option types are no longer possible in OFN

app/views/spree/admin/shared/_product_sub_menu.html.haml

@@ -1,6 +1,5 @@
 - content_for :sub_menu do
   %ul#sub_nav.inline-menu
     = tab :products, match_path: '/products'
-    = tab :option_types, match_path: '/option_types'
     = tab :properties
     = tab :prototypes