Add installer verification to our CI

At the moment, our testing checks if the qt app works when running naively in python, but not when installed.

For this, we need to figure out how to test a deployed QT app, either by simulating clicks, or as I've done in the past, actually bundle pytest with the application itself.

Pytest is pretty light, so if it only increases the app size by a MB or two, why not? We could have the option to disable bundling the testing env as well.

This way, we can just start the app in testing/validation mode with:

```
.exe --test
```

This way, once installed we'd figure out the install location (should be just default `%ProgramFiles%\ANSYS Inc\\` and run the unit testing from the installed application.