Consistently record host.id as a resource attribute

[mwear]

Is your feature request related to a problem? Please describe.

I would like to be able to consistently record host.id as a resource attribute. The spec has the following description:

Unique host ID. For Cloud, this must be the instance_id assigned by the cloud provider. For non-containerized Linux systems, the machine-id located in /etc/machine-id or /var/lib/dbus/machine-id may be used.

The cloud provider resource detectors (aws ec2, gcp, etc) add the host.id as spec'd but we don't have a way to easily add it for non-cloud hosts.

Describe the solution you'd like

I propose collecting the host.id in the existing HostDetector, which currently only collects non-cloud host attributes. Depending on OS there are files that can be read, or commands that can be executed to obtain the machine id. There is a well used library, nodde-machind-id that handles machine id discovery for *nix, MacOs, and Windows. We can use it, or write something comparable ourselves if we'd rather avoid a dependency.

Describe alternatives you've considered

If we don't think this functionality belongs in HostDetector we could introduce it in a separate detector.

Additional context

I'm planning to do this work and will open a PR shortly. We can continue discussions here and/or there.

[dyladan]

@mwear did you open a spec issue for this?

[mwear]

I have a spec PR here: open-telemetry/opentelemetry-specification#3173