Drop Spree::Core::TokenResource

None of spree components use that feature except for the token attribute
itself which we could just move to Order so we can run less things when
creating an object

Been trying to review all queries executed while creating and completing orders (orders.contents.add still run a ton of stuff I think we should try harder to improve) and noticed this tokenized_permission table. Does anyone see a good reason to keep it in spree core? This is still missing a migration, will add it in case we agree this association should be dropped.