`http.response.status_code` normalization for Metrics & Alerts

[kahest]

Background:

http.status is set in different places in different SDKs which creates some problems in processing for metrics extraction and then

https://www.notion.so/sentry/Expand-Metrics-for-Alerts-cdfa32d7624e498b8246c3f131f753f1#17480955e2fb4407b619b9236bc2723a

Requirements:

• Need status code number (standard HTTP status code 2xx, 4xx, 5xx, etc)
• The SDK should never on it's own set this as a tag - as this adds expense due to indexing being based on tags
• the location of storage needs to be in a standard location based on span schema
  • follow existing standard in develop docs
  • of not starfish has a workstream to standardize span schema rfc(feature): Aligning the Span Schema with OpenTelemetry rfcs#89

Note: .NET and Java are handled in getsentry/team-sdks#9.

### Validate Per SDK and check as is
- [ ] https://github.com/getsentry/sentry-cocoa/issues/3076
- [ ] https://github.com/getsentry/sentry-dart/issues/1473
- [x] https://github.com/getsentry/sentry-java/pull/2786
- [x] React Native

[romtsn]

We'll look into the code base and check if anything has to be done and check off the platform if nothing is needed.

[marandaneto]

@antonpirker this doc is related to this issue right?
We just need to be sure what the schema is, so we can double-check in our implementation.

[marandaneto]

https://develop.sentry.dev/sdk/performance/span-operations/ does not tell where http.status should go.
getsentry/rfcs#89 is a draft and it links to OTel which is a huge breaking change.

[marandaneto]

getsentry/develop#940 is the spec, I believe SDKs don't set that yet, so we have to.

[antonpirker]

@antonpirker this doc is related to this issue right? We just need to be sure what the schema is, so we can double-check in our implementation.

Maybe too late, but for the record: Yes. this doc is "where are all the SDKs storing the http status code right now". In the future we want all the SDKs store the http status code in the same place, making it easier of ingest to act on it.