resource monitor support

Add support for monitoring system resources to detect resource leaks and similar issues.

We can call `free`, `ps`, and others before and after running a test case, then check whether all resources have been properly freed.

This feature should be optional and configured from the YAML config, as it will not always be available.

Start by locating the YAML configuration handling and the test-case execution path in the Python framework. Review how `free`, `ps`, and similar commands can be run before and after a test, then define the optional configuration and the resource-check result that indicates resources were properly freed.

Written by the indexing model from the issue text.