feat: add Knative serving dependency and app service config structs

[AdilFayyaz]

Why are the changes needed?

The App Service needs to manage Knative KService CRDs to deploy and stop long-running apps. This PR lays the foundational infrastructure — dependency, scheme registration, and config — that subsequent PRs will build on.

What changes were proposed in this pull request?

• Add knative.dev/serving v0.40.2 (pinned to a version compatible with the repo's existing k8s.io v0.28.x constraints)
• Add actions/k8s/app_scheme.go: InitAppScheme() registers KService, Route, Configuration, and Revision types into the client-go scheme so the K8s client can work with KService CRDs
• Add AppConfig to actions/config: feature flag, KService namespace, and request timeout bounds
• Add AppsConfig to runs/config: public URL pattern template and internal app service URL for the control-plane proxy
• Moved the files in app/ to flytestdlib/ and respectively the call sites as well

How was this patch tested?

• go build ./actions/... ./runs/... passes with no errors
• go mod tidy is clean with no missing or unused dependencies
• Existing packages that use golang-lru (upgraded v0.5.4 → v1.0.2 as a transitive side effect) were verified: go build
  ./flytestdlib/... ./flyteplugins/... passes — v1.x preserves the non-generic API used by this repo

Setup process

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Check all the applicable boxes

• I updated the documentation accordingly.
• All new and existing tests passed.
• All commits are signed-off.

Related PRs

Docs link

• main
  • Flyte 2 WIP #6583
    • feat: add Knative serving dependency and app service config structs 👈
      • feat: add AppK8sClient for KService lifecycle management #7166