Feature Request: Add CustomErrorRegularExpression & more to ToolTask/XamlTaskFactory

There are several useful features in the Exec Task that would be great to be able to use from a ToolTask/XamlTaskFactory.

If we use an Exec task directly, that allows us to use CustomErrorRegularExpression.

We currently use XamlTaskFactory for some external tools, but would like to customize the output error parsing. However that does not seem possible at the moment. Or is there another way to have the XamlTaskFactory be customized for error parsing?

Since the Exec/ToolTask/XamlTaskFactory are all ways of running external tools, it would be great if they had a more common api to customize behaviour.