[sqlite] Add keyservers_synced_data table

Summary:
Part of ENG-6927 : Stop backing up device specific data in keyserverStore

Because we only want to back up part of keyserver store, the easiest way to implement this is to create a separate table and backup only one them. This table creates the new keyservers_synced_data table.

Depends on D11472

Test Plan: Run migration on web and native, make sure the table is created.

Reviewers: kamil, marcin

Reviewed By: kamil, marcin

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D11473