Add specification for ASN/Autonomous System Number

Area(s)

area:network

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

Including the ASN in OpenTelemetry tracing data is helpful when trying to analyze where an attack is coming from. Often attackers use multiple IPs that come from the same ASN. Also, it can be helpful for diagnosing if an issue is specific to one network, or many networks.

Describe the solution you'd like

Add a standard attribute for specifying an ASN, and possibly the ASN name. E.g.

network.as.number
network.as.organization.name

(Borrowing heavily from https://www.elastic.co/guide/en/ecs/current/ecs-as.html).

Describe alternatives you've considered

I can just add this myself, but it seems like a common use.

Additional context

Perhaps this should be available for many different parts of the schema that deal with IP addresses, e.g. client.as.number, destination.as.number.