Another step in the Ext proc refactoring

[shmuelk]

What type of PR is this?
/kind cleanup

What this PR does / why we need it:
Both the Endpoint Picker (EPP) and the Body Based Router (BBR) are Envoy ExtProc filters. There is much code that has been copy and pasted from one to the other.

This PR is in a series of PRs that will refactor out the common Ext Proc processing code into a set of reusable packages. This is being done to try and keep the PRs somewhat smaller.

In particular this PR refactors packages, some code is moved to the common package, and the StreamingServer is renamed.

Which issue(s) this PR fixes:

Ref: #2427

Does this PR introduce a user-facing change?:

NONE

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: shmuelk
Once this PR has been reviewed and has the lgtm label, please assign danehans for approval. For more information see the Code Review Process.

The full list of commands accepted by this bot can be found here.

Details

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[netlify]

✅ Deploy Preview for gateway-api-inference-extension ready!

Name	Link
🔨 Latest commit	65a64fb
🔍 Latest deploy log	https://app.netlify.com/projects/gateway-api-inference-extension/deploys/69b6a3cb56fa7d0008d5b6a0
😎 Deploy Preview	https://deploy-preview-2560--gateway-api-inference-extension.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify project configuration.

[k8s-ci-robot]

PR needs rebase.

Details

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[ahg-g]

Are you planning to rebase and merge the PR in this repo? or close and work on this after the migration?

[shmuelk]

I'm not sure this PR is relevent, as the EPP is moving to the llm-d-inference-scheduler and the bbr is moving to a different repo.

Opinions?

[nirrozenbaum]

I'm not sure this PR is relevent, as the EPP is moving to the llm-d-inference-scheduler and the bbr is moving to a different repo.

Opinions?

+1 on closing