[Example] Autograd and run_snode examples run now; added smoke tests

[hughperkins]

Issue: #

Brief Summary

Autograd and run_snode examples run now; added smoke tests

copilot:summary

Walkthrough

• neither autograd nor run_snode examples ran: both resulted in a seg fault
• fixed both so that they run without seg-faulting now
  • note that there is still at least one bug remaining: the return value doesn't relate to what is returned inside the kernel
  • however they do run without crashing now
• added smoke tests, that check that the examples run without crashing, i.e. return code from running is 0.

Some questions/caveats:

1. I found I had to expose the create_load parameter to IRBuilder::create_arg_load, and set this to false in the examples
   • the default true caused a seg fault
   • I'll provide examples of the IR with load set to false and true below, in case that gives any ideas
2. In order to run the smoke tests, I simply created a python script, that runs them from build folder. This seems like maybe not the most robust way? Open to ideas/suggestions on a more robust way of locating them (I suspect this won't work on Windows for example, though I guess we will see when CI tests run; I can always disable them from running in Window, in the short-term)

copilot:walkthrough