move Golang extension from contrib to standard

[doujiang24]

Motivation

Make people use the standard version with confidence.
Some people have expressed concerns about the contrib version, i.e. the thread in enovy-go slack channel.

Status

The latest envoy 1.28.0 should be stable enough.
All knowned bug are fixed in envoy 1.28.0. And no new bugs reported since 1.28.0.

Nearly ~100 improvements, and ~5 bugfixes since first merged in contrib.
i.e. retired the GODEBUG=cgocheck=0 env requirement.

Test

• fuzzer: golang filter extension: simple fuzz for downstream input. #25884
• test coverage
• test flake: IpVersions/GolangIntegrationTest.DynamicMetadata_Async_Sleep/IPv6 flake #31654

Doc

There are some baisc doc about how to develop and build plugin, and examples for how to implement golang plugins.

• need more detailed doc about the Go APIs, for implementing Golang plugins.

Question

In addition to these TODOs, what else needs to address? Or, any other requirements?
cc @mattklein123 @alyssawilk @phlax @wbpcode Any advice & guidance? Thanks very much!

Maybe it could be done in the 1.31 release? if there are no big blocking issue.

[alyssawilk]

This list looks great to me. The one thing I think you're missing is maintainer sponsorship - not sure if you've already gotten someone to sign on or if you want to cc the maintainers list and see who is game for sponsoring.

[doujiang24]

Thank you for your kind words. We don’t have a maintainer sponsor yet. Would you be interested in sponsoring us? It would be an honor for us. 🙏

[alyssawilk]

Unfortunately good as I think the extension is, I don't have the cycles to spin up context and do reviews.
@envoyproxy/envoy-maintainers anyone game to take this one on? I think it's a good addition to the project and @doujiang24 has been doing fantastic work with bug fixes so hopefully sponsorship wouldn't be a large burden.

[wbpcode]

I think there may be huge of review work to move this extension.

I can help in code quality but I am not familiar with the cgo, so we still need another maintainer who are familiar to or at least interest in that.

[ADustyOldMuffin]

I'd like to add an extra comment for the docs side, the lifecycle of all of the functions and golang features (like the unit function, vars, etc) should be documented to help people.

[github-actions]

This issue has been automatically marked as stale because it has not had activity in the last 30 days. It will be closed in the next 7 days unless it is tagged "help wanted" or "no stalebot" or other activity occurs. Thank you for your contributions.

[Olshansk]

@doujiang24 We're currently considering using this for production mission-critical services. Do you think the golang extension are in that stage?

[doujiang24]

@Olshansk Yep, I think it's ready for production, we have using it in production over a year.

The main risk comes from the stability of the API.
However, this is not a big problem. What this means:
When you upgrade Envoy, you need to upgrade Go-SDK to the corresponding version and recompile the golang plugin.
If there are API changes, you may need to change the way the API is called.