Fix for 'multiple post' - run handlers for each created resource

Summary: Before the fix running multiple post on a collection wouldn't trigger handler listening for 'create' on that collection

Test Plan: make test

Reviewers: #reviewers, piotr-ptaszynski

Reviewed By: #reviewers, piotr-ptaszynski

Subscribers: piotr-ptaszynski

Differential Revision: https://hub.sealcode.org/D273