Add ability to call a VI as Custom Execute

[CL_eisenwr]

This probably applies more to building a NI Package via Application Builder, but would be helpful if you could do it with NI Package Builder (NIPB). It should be easier to call a VI(s) as a custom execute steps of a package. You can do this currently by making your VI follow the LabVIEW CLI pattern. However this does requiring a lot of manual entry from the user to do in NIPB, thus being error prone. Also to do with the Application Builder, you have to make a batch file and add that to project even thought the batch fill does not need to exist other than to do the install/uninstall.