fix: Add AtClientException in SyncProgress and return exception on invalid sync regex

[sitaram-kalluri]

- What I did
fix: Add AtClientException in SyncProgress and return exception on invalid sync regex

• When an invalid regex is supplied to the AtClientPreferences, the sync service fails to fetch the localCommitId. In at_persistence_secondary_server, "AtCommitLog.lastSyncedEntryWithRegex" returns an FormatException when trying to fetch the lastSyncedEntry with regex, but the exception is not propagated to apps. Since the sync service is unable to fetch the localCommitId, it enters into an infinite loop but the underlying reason is unknown to the apps.

• Removed the tearDown method in notify_test.dart which removes the KeyStore files after the notify test and as a result the subsequent tests will have to perform the initial sync.

• Removed the imports from following files that cause warnings in the dart analyze

  • at_client_impl.dart
  • at_client_manager.dart
  • at_client_impl_test.dart
  • no_op_services.dart

- How I did it

• In the sync progress, Introduce AtClientException.
• When fetching localCommitId, if a FormatException arises, catch the exception and populate the AtClientException in the SyncProgress and inform the apps.

- How to verify it

• Added a unit test to assert the changes.

- Description for the changelog

• Return AtClientException from sync service when an invalid regex is supplied in the AtClientPreferences.

[gkc]

@sitaram-kalluri this PR's branch has git conflicts that need to be resolved

[sitaram-kalluri]

@sitaram-kalluri this PR's branch has git conflicts that need to be resolved

Sure Gary, will resolve it and keep you updated.

[sitaram-kalluri]

@gkc: Resolved the merge conflicts. Please review.