Implement draft store operations processing in CommCoreModule

Summary: This differential implements draft store processing functionality in CommCoreModule to enable bulk drafts dump to SQLite.

Test Plan: Make sure eslint and flow do not point errors.

Reviewers: tomek, atul, jon

Reviewed By: tomek, atul

Subscribers: ashoat, abosh

Differential Revision: https://phab.comm.dev/D5648