[lib] Migrate DeleteEntry/RestoreEntry notifTexts to use EntityText

Summary: Depends on D6576

Test Plan: Generated DeleteEntry and RestoreEntry messages on a web client in a chat with a different test user that is logged in on the iOS simulator. Background the iOS app and make sure the notif looks right

Reviewers: atul

Reviewed By: atul

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D6577