feat: Add connector EnvoyPatchPolicy for HTTPProxy backends

[zachsmith1]

• Adds connector‑aware EnvoyPatchPolicy generation for HTTPProxy backends, including corrected JSONPath filters aligned with Envoy Gateway route metadata so patches apply as intended.
• Ensures downstream ownership/cleanup via mapped‑namespace anchor configmaps and removes anchors when policies are deleted or no longer needed.
• Gates HTTPProxy Programmed status on downstream patch policy Accepted/Programmed when connector backends are present, with clearer status messaging.
• Watches downstream EnvoyPatchPolicy status to re‑reconcile HTTPProxy on policy changes.
• Expands HTTPProxy reconcile tests to cover downstream namespace/anchor setup and updated status expectations.
• Verified end‑to‑end by loading the operator image and confirming routes get patched cluster + headers. (e2e test will come in a different PR)

Ref: datum-cloud/enhancements#556
Ref: datum-cloud/enhancements#483
Ref: datum-cloud/enhancements#508