Ability to specify prometheus labels with rpk generate command

[bpraseed]

Who is this for and what problem do they have today?

Users having multiple redpanda deployments would like to differentiate between instances using a label.

What are the success criteria?

rpk generate prometheus-config to have the ability to specify label for a redpanda cluster
https://prometheus.io/docs/prometheus/latest/configuration/configuration/#:~:text=labels%20assigned%20to%20all%20metrics%20scraped%20from%20the%20targets.

Why is solving this problem impactful?

Collision of metrics if no label is specified and hard to track in Prometheus if a customer has multiple redpanda instances.