ChangeFeedProcessor: Adds ChangeFeedProcessorUserException for detailed error notification

[ealsur]

#2787 missed adding ChangeFeedProcessorUserException to the GA package.

This type is useful to distinguish internal from user-related errors when creating on error notifications:

var notifyErrorAsync = (string LeaseToken, Exception exception) =>
    {
        if (exception is ChangeFeedProcessorUserException userException)
        {
             Console.WriteLine($"Lease {LeaseToken} processing failed with unhandled exception {userException.InnerException}");
             Console.WriteLine($"Diagnostics {userException.ExceptionContext.Diagnostics}");
             Console.WriteLine($"Headers {userException.ExceptionContext.Headers}");
        }
       else
       {
           // This could be matched for CosmosException to decide importance based in our guidelines
            Console.WriteLine($"Lease {LeaseToken} failed with {exception}");
       }
     } ;

ChangeFeedProcessor changeFeedProcessor = monitoredContainer
	.GetChangeFeedProcessorBuilder<ToDoItem>(processorName: "changeFeedSample", HandleChangesAsync)
		.WithInstanceName(instanceName)
		.WithErrorNotification(notifyErrorAsync)
		.WithLeaseContainer(leaseContainer)
		.Build();

[github-actions]

Please follow the required format: "[Internal] Category: (Adds|Fixes|Refactors|Removes) Description"

Internal should be used for PRs that have no customer impact. This flag is used to help generate the changelog to know which PRs should be included. Examples:
Diagnostics: Adds GetElapsedClientLatency to CosmosDiagnostics
PartitionKey: Fixes null reference when using default(PartitionKey)
[v4] Client Encryption: Refactors code to external project
[Internal] Query: Adds code generator for CosmosNumbers for easy additions in the future.

All good!