Initial Inference Extension Plugin

[danehans]

Description

Adds initial support for an inference extension endpoint picker plugin. The plugin will:

1. Contributes an Upstream based on an InferencePool.
2. Creates the endpoints collection based on namespace-local Pod IPs from the InferencePool selector.
3. Creates an Envoy ORIGINAL_DST from the InferencePool-generated.

API changes

N/A

Code changes

• Adds inferenceextension/endpointpicker pkg
• Updates krtcollections pkg to transform InferencePool endpoints into Upstream endpoints.
• Bumps go deps for inference extension pkg
• Runs code generators due to go dep bump.

CI changes

N/A

Docs changes

Godocs added throughout. User docs will be added in a future PR.

Context

Supports #10411

Interesting decisions

To keep the PR small, this is the first of multiple PRs to implement the endpoint picker plugin. This PR _does not create the ext-prc cluster nor does it add the ext-proc filter to the listeners filter chain.

Testing steps

Unit tests were added. e2e tests are still required and not included here due to the size of the PR.

Notes for reviewers

Refer to the upstream docs for add'l context.

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works

[danehans]

Note: To pass CI, this PR includes a few identical commits as #10676 for go mod bump, code generations, etc.