[web] Rename database worker
Summary:
ENG-6648 : Refactor database worker
The database worker will now contains code not related to the database (e.g. cryptoStore and other crypto related operations) so I'm renaming it to a general shared-worker.
Depends on D11143
Test Plan: Check that the app works, click around, check that the database works.
Reviewers: kamil, tomek
Reviewed By: kamil
Subscribers: ashoat
Differential Revision: https://phab.comm.dev/D11236