fetch current container runtime config through the command line

[tariq1890]

In this PR, we change how the baseline container runtime configuration is fetched when using containerd/crio.

We now know that neither /etc/containerd/config.toml nor /etc/crio/crio.conf files provide a complete picture of the current configuration. To address this gap, we run the containerd config dump or crio status config commands to get the complete runtime configuration that reflects the current state.

This PR has been tested in the following scenarios

i) nvidia-ctk runtime configure --runtime=containerd - Standalone
ii) nvidia-container-toolkit daemonset - GPU Operator Stack

[elezar]

Thanks for starting on this @tariq1890. I was thinking a bit on how to implement this and created #643 (more from a refactoring perspective).

The idea is that we introduce an interface that returns a *toml.Tree when called. We then have different implementations of this for:

1. a .toml file.
2. a command such as containerd config dump
3. a direct query to the cri socket (not yet implemented).

This has the benefit that we can separate the construction of this Source / Reference from its use in the various runtimes.

What are your thoughts?

[tariq1890]

Thanks @elezar . I have opened a new PR with your refactoring changes: #686

[elezar]

Does #686 replace this? If so, can we close this PR?