Use otel4s-semconv-metrics-experimental for semantic testing

[iRevive]

Here is an example of the 'semantic conventions tests'.

[iRevive]

We've spotted the first mismatch 🥳

[iRevive]

The current implementation of the MetricOps is rather limiting and we cannot comply the spec.

I don't think we should make drastic changes to 0.23, but we can to 1.0.x: http4s/http4s#7491.

[NthPortal]

it seems I'll need to poke at updating the implementations of the tracing middlewares to be correct

[NthPortal]

@iRevive I rebased, fixed the conflicts, and force pushed. how do you want to proceed given that the current implementation from 0.23.x doesn't support some attributes? should we add logic to specifically skip the checks for those attributes and add a TODO comment to fix it in a later release? should we wait until we actually have a compliant implementation to fix it? something else?

I don't think we should make drastic changes to 0.23, but we can to 1.0.x

it should be possible to do it in a binary compatible way in 0.23.x, though it would be a pain. but would it be worth it anyway, as it may yet be many years until 1.0.x is released?

[iRevive]

should we wait until we actually have a compliant implementation to fix it?

I think it would be the easiest option for us.

[NthPortal]

@iRevive are the equivalent semantic tests for tracing? also, the fix to the counter description should probably get its own PR so it can be merged

[iRevive]

@NthPortal no, there is no such testing for traces, unfortunately.

the fix to the counter description should probably get its own PR so it can be merged

I will make a PR.

[NthPortal]

@iRevive I discovered from #177 that http4s has types suffixed with numbers (such as WebSocketBuilder2) from when new, incompatible APIs needed to be introduced in a binary-compatible manner because the old APIs were bad or insufficient. it may be possible and worthwhile to introduce a MetricsOps2 to http4s to support the needs of otel4s (and potentially other telemetry libraries, but primarily otel4s)

[iRevive]

it may be possible and worthwhile to introduce a MetricsOps2 to http4s to support the needs of otel4s

That would be nice. Maybe we can reuse some ideas from my PoC branch: http4s/http4s#7491