Move to MEF-based or Automation registration for rules

Currently all of our rule XAML files are shipped on disk, but they're also included as resources in the DLLs, which is superfluous. We need to see if we can move to MEF Export or Automation in order to expose the rules. See here for information: https://github.com/Microsoft/VSProjectSystem/blob/master/doc/extensibility/adding_xaml_rules.md#via-mef-export

If this is possible then we can stop shipping XAML files to users.