CI for building standalone examples

[jfdev001]

It's yours @jfdev001 and thanks for the details and looking into this.

Indeed, it was something I thought about last night that we should perhaps have a separate 'standalone examples' CI job.

Originally posted by @jatkinson1000 in #435

The examples that get run as part of integration testing are built using libftorch.so that is generated by the build phase (i.e., cmake --build .) but this does not guarantee functionality of the libftorch.so that gets generated by the install phase (i.e., cmake --install .). Since the user will link against the libftorch.so that is generated by the install phase, it makes sense to provide CI that checks to make sure "standalone examples" run using the installed library target. See #435 (comment) for more details.

Related also to #304