Config: Review client config file format and management

[rtamalin]

Currently the client config file is a YAML file and the telemetry client library leverages the gopkg.in/yaml.v3 package to access it.

However this library doesn't appear to be be well maintained, with many open issues, and no code activity in approx 2 years. Therefore, switching to a better maintained package to provide YAML parsing capabilities would appear to be a good idea, with sigs.k8s.io/yaml looking to be the best candidate.

Alternatively we could just switch to a JSON file, though doing so would complicate matters as regards supporting comments into the config file.

Alternatively we could implement a simplified YAML-like format similarly to how SUSE/connect-ng manages it's config file.

[rtamalin]

This may have implications for #7