Support Expressions for Custom Step Type Icons

[Al.B]

Currently, the step icon for a custom step type is defined statically:

 It would be nice if the step icon could also be specitied via expression.  This would allow step types where the step icon changes based on the configuration.  For example, the lock step could be made more intuitive:

Current static icon:

With dynamic icons:

To accomplish this currently, you need to update the icon for the step via the API in the edit substep, which is cumbersome and adds coupling between the edit substep code and the icon names.

[Bluegraf]

The need for this shines through in some older forum discussions:

https://forums.ni.com/t5/NI-TestStand/where-icons-are-stored/td-p/2328294

https://forums.ni.com/t5/NI-TestStand/TestStand-Public-Target-folder/td-p/932735

https://forums.ni.com/t5/NI-TestStand/Is-there-a-way-to-assign-the-TestStand-User-Components-Directo...

Also a related suggestion with some Kudos can be found here:

https://forums.ni.com/t5/NI-TestStand-Idea-Exchange/custom-Icon-can-be-loaded-from-search-directory/...

It would be great to merge the ideas and kudos to make this idea more visible...

Expressions would also allow my usecase: Load the icon not from some a generic TS path that changes in every release but rather from someting like:

C:\[MyCompanyName]\[MyTesterProject]\TestTypes\Icons\[IconForTHISTestType].ico