Refactor camkes simulation tests to use CTest

CTest allows the tests to be better integrated with the project build
configuration. This makes maintaining and adding tests easier. It also
makes it possible to run the tests as part of a development workflow
with a near-instant incremental rebuild instead of having to configure
and build a full project from scratch.

Add hellorust camkes component

This demonstrates building a rust library and linking it into a camkes
component. Only x86_64 is currently supported