rgw: integrate perf counters cache

Signed-off-by: Ali Maredia <amaredia@redhat.com>

common: PerfCountersCache using intrusive_lru

This cache is meant to hold labeled perf counters

Signed-off-by: Ali Maredia <amaredia@redhat.com>

common: ceph::perf_counters::cache_key_insert()

Signed-off-by: Casey Bodley <cbodley@redhat.com>

common: ceph::perf_counters::make_cache_key()

a flat representation of a set of prometheus labels, returned as a
std::string. this string can either be used for sorting an ordered
container of perf counters, or for hashing an unordered container

use a variadic template to initialize a temporary array for sorting

use rvalue-ref to c array instead of variadic template

Signed-off-by: Casey Bodley <cbodley@redhat.com>

Merge pull request #47582 from snosratiershad/docs/correct-add-system-user-to-the-master-zone-command

docs: correct add system user to the master zone command

Reviewed-by: Zac Dover <zac.dover@gmail.com>