provide a way to listen for account remove callback from background; unify permissions across adding and removing account.

Description

changes required to migrate our other apps to in house account added and removed broadcast.

Technical details

We have migrated our mail app to use an in-house broadcast implementation instead of the system one.
Our custom implementation is more robust and handles edge cases more effectively.
This change lays the foundation for migrating our other apps to use our custom broadcast as well.

Tests

manually tested by adding and removing account. see testing in AccountManager#176

Issues

see 3705

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Summary by CodeRabbit

• Bug Fixes
  • Improved reliability of notifications sent to mail apps after account creation and removal, reducing missed or delayed updates across devices and OS versions.
• Refactor
  • Internal account-notification mechanism updated and simplified, removing legacy behavior for easier maintenance and fewer edge-case failures.