Support array_value attribute type

[fularac]

Would be helpful for sending the the header.(request|response).header.<key> for following the http conventions: https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/semantic_conventions/http.md#http-request-and-response-headers

HTTP request and response headers

Attribute	Type	Description	Examples	Requirement Level
http.request.header.<key>	string[]	HTTP request headers, <key> being the normalized HTTP Header name (lowercase, with - characters replaced by _), the value being the header values. [1] [2]	http.request.header.content_type=["application/json"]; http.request.header.x_forwarded_for=["1.2.3.4", "1.2.3.5"]	Opt-In
http.response.header.<key>	string[]	HTTP response headers, <key> being the normalized HTTP Header name (lowercase, with - characters replaced by _), the value being the header values. [1] [2]	http.response.header.content_type=["application/json"]; http.response.header.my_custom_header=["abc", "def"]	Opt-In

P.S. thank you for all your work so far!

[yangxikun]

Do you mean add two method to get http header attributes for span, just like golang sdk:

https://github.com/open-telemetry/opentelemetry-go/blob/f15ae160c4acfe3872455f87e6133af87859172b/semconv/internal/v4/http.go#L299

https://github.com/open-telemetry/opentelemetry-go/blob/f15ae160c4acfe3872455f87e6133af87859172b/semconv/internal/v4/http.go#L304

[fularac]

Those helper functions would be useful too!

Looking into the ppentelemetry/attribute.lua it's missing the <type>Slice versions as found in https://github.com/open-telemetry/opentelemetry-go/blob/69611bd01a355466f324cca84068f54e6e388654/attribute/value.go#L40-L59

[yangxikun]

I will try to implement this.