Update OM2.0 for UTF-8 metric names and labels

[ywwg]

part of prometheus/prometheus#16093

[krajorama]

looks good, one nit comment

[krajorama]

looking good, I think need some examples with CI check on them

[krajorama]

@ywwg I'd suggest to scan the "Design considerations" section, in particular https://prometheus.io/docs/specs/om/open_metrics_spec/#metric-naming-and-namespaces .

I've done it as a follow-up to relaxed suffix rules, see #2751

[bwplotka]

Looks good to me, thanks for extending!

I assume we will follow with same/similar wording in 2.0, right?

Can we outline e.g. in the description of this PR why we add UTF-8 capability to 1.1 instead of releasing this change with 2.0? Would be useful for bookkeeping.

[ywwg]

we are going to go directly to 2.0 and skip 1.1 after all, so I'll adapt this change to 2.0 instead

[ywwg]

(I am not deleting 1.1 because we need to port some more changes from it into 2.0 and it's useful to keep it around for now)

[krajorama]

to fix CI fail

[ywwg]

removed diffs with 1.1 and cleaned things up a bit

[krajorama]

Looks good. I really think we should add some examples that are checked against the ABNF. It's ok if you want to do it in a next PR as well.

[ywwg]

Yeah can we do that in a followup? I'll file an issue

[ywwg]

#2766