Implement DraftStoreOperations C++ utility

Summary: This differential implements DraftStoreOperations C++ utility to convert drafts related redux actions payloads to DatabaseQueryExecutor calls.

Test Plan: This differential only introduces C++ header file, so it is not possible to create test plan.

Reviewers: tomek, atul, jon

Reviewed By: tomek, atul

Subscribers: ashoat, abosh

Differential Revision: https://phab.comm.dev/D5647