SyncEngine should inspect errors to determine retry advice

[palpatim]

As noted in the TODO in this code snippet https://github.com/aws-amplify/amplify-ios/blob/4cb4423a6eb3d46dc0caf4bf55392384b0e4acc8/AmplifyPlugins/DataStore/AWSDataStoreCategoryPlugin/Sync/RemoteSyncEngine+Retryable.swift#L31-L39

We do not currently respect error types when retrying sync errors; instead we always retry errors up to the limit, regardless of the incoming type. We should not retry error types that aren't considered retryable (e.g., 403, 404, etc)

[atierian]

It looks like this has been resolved through:

• fix(DataStore): retry initial sync network failures from RemoteSyncEngine #1773
• fix(datastore): retry on subscription connection error #2571

See getRetryAdvice(error:) -> RequestRetryAdvice for current implementation.