[Housekeeping] Migrate protobuf stub generation to buf

[eapolinario]

Describe the issue

We currently rely on a series of old (and very-hard-to-update) code to generate the stubs for the different languages we support in flyteidl.

Instead we should leverage buf and move over the step at which we generate the stubs, e.g. if we adopt buf remote plugins we don't even have to maintain generated stubs.

What if we do not do this?

It's nearly impossible to update the original script, this makes it hard for us to adopt newer technologies, for example grpc-gateway v2 (which includes the swagger/openapiv2 annotations).

Related component(s)

flyteidl

Are you sure this issue hasn't been raised already?

• Yes

Have you read the Code of Conduct?

• Yes

[github-actions]

Hello 👋, This issue has been inactive for over 9 months. To help maintain a clean and focused backlog, we'll be marking this issue as stale and will close the issue if we detect no activity in the next 7 days. Thank you for your contribution and understanding! 🙏

[github-actions]

Hello 👋, This issue has been inactive for over 9 months and hasn't received any updates since it was marked as stale. We'll be closing this issue for now, but if you believe this issue is still relevant, please feel free to reopen it. Thank you for your contribution and understanding! 🙏