prometheus API: Add label support
prometheus API: Add label support

This adds the labels that are passed in the id as labels.

Signed-off-by: Amnon Heiman <ed5fc74c4692051ad0b19749fd7cea6ec2d74b9e@scylladb.com>

cloudius-systems/seastar,syuu1228/seastar,dreamsxin/seastar,cloudius-systems/seastar,dreamsxin/seastar,scylladb/seastar,dreamsxin/seastar,syuu1228/seastar,cloudius-systems/seastar,syuu1228/seastar,avikivity/seastar,avikivity/seastar,scylladb/seastar,avikivity/seastar,scylladb/seastar