[native] Replace Redux with jsi for drafts

Summary: Replaces Redux code responsible for handling drafts with jsi calls to the local sqlite database.

Test Plan: run native app, compose a message in a thread, change the navigation without sending a message, come back to the same thread and see whether the message's still there. Also, after message is sent, check if draft does not exist anymore.

Reviewers: palys-swm, ashoat

Reviewed By: ashoat

Subscribers: ashoat, KatPo, palys-swm, Adrian, atul

Differential Revision: https://phabricator.ashoat.com/D1051