SemConv: Missing attributes with `<key>` suffix

[florianl]

Description

Semantic Conventions uses keys, that are not static - e.g. process.environment_variable..

In otel-go v1.37.0 with sem-conv v1.34.0 (at least) the following semantic convention attributes are missing:

process.environment_variable.<key>
http.request.header.<key>
http.response.header.<key>

Environment

otel-go: v1.37.0 with sem-conv: v1.34.0

[MrAlias]

@florianl as a user, what form would you like to see these provided in? Would something like this be suitable?

func ProcessEnvironmentVariable(key, val string) attribute.KeyValue

func HTTPRequestHeader(key string, val ...string) attribute.KeyValue

func HTTPResponseHeader(key string, val ...string) attribute.KeyValue

[florianl]

The suggestions, ProcessEnvironmentVariable(), HTTPRequestHeader() and HTTPResponseHeader(), sound all good to me.