[services] Backup - Send log - add backup id and log hash states

Summary:
Depends on D3646

Adding two missing states for the reactor: BACKUP_ID and LOG_HASH. along with the cases in the reading request method's body.

Test Plan:

cd services
yarn run-backup-service

Reviewers: palys-swm, geekbrother

Reviewed By: palys-swm

Subscribers: ashoat, palys-swm, Adrian, atul, benschac, yayabosh

Differential Revision: https://phabricator.ashoat.com/D3647