use peer_metadata to get pod metadata info from istiod

[YaoZengzeng]

What type of PR is this?

/kind enhancement

use peer_metadata http filter to get pod metadata from istiod

What this PR does / why we need it:

So we could get necessary fields to fill observability information

Before this modification, the metric is :

istio_requests_total{reporter="destination",source_workload="unknown",source_canonical_service="unknown",source_canonical_revision="latest",source_workload_namespace="unknown",source_principal="unknown",source_app="unknown",source_version="unknown",source_cluster="unknown",destination_workload="reviews-v1",destination_workload_namespace="default",destination_principal="unknown",destination_app="unknown",destination_version="unknown",destination_service="reviews.default.svc.cluster.local",destination_canonical_service="reviews",destination_canonical_revision="v1",destination_service_name="reviews",destination_service_namespace="default",destination_cluster="Kubernetes",request_protocol="http",response_code="200",grpc_response_status="",response_flags="-",connection_security_policy="none"} 93

After this modification:

istio_requests_total{reporter="destination",source_workload="productpage-v1",source_canonical_service="productpage",source_canonical_revision="v1",source_workload_namespace="default",source_principal="unknown",source_app="productpage",source_version="v1",source_cluster="Kubernetes",destination_workload="reviews-v1",destination_workload_namespace="default",destination_principal="unknown",destination_app="unknown",destination_version="unknown",destination_service="reviews.default.svc.cluster.local",destination_canonical_service="reviews",destination_canonical_revision="v1",destination_service_name="reviews",destination_service_namespace="default",destination_cluster="Kubernetes",request_protocol="http",response_code="200",grpc_response_status="",response_flags="-",connection_security_policy="none"} 1

And the metric from waypoint in ambient mesh:

istio_requests_total{reporter="destination",source_workload="productpage-v1",source_canonical_service="productpage",source_canonical_revision="v1",source_workload_namespace="default",source_principal="spiffe://cluster.local/ns/default/sa/bookinfo-productpage",source_app="productpage",source_version="v1",source_cluster="Kubernetes",destination_workload="reviews-v1",destination_workload_namespace="default",destination_principal="spiffe://cluster.local/ns/default/sa/bookinfo-reviews-istio-waypoint",destination_app="unknown",destination_version="unknown",destination_service="reviews.default.svc.cluster.local",destination_canonical_service="reviews",destination_canonical_revision="v1",destination_service_name="reviews",destination_service_namespace="default",destination_cluster="Kubernetes",request_protocol="http",response_code="200",grpc_response_status="",response_flags="-",connection_security_policy="mutual_tls"} 34

We have basically filled in all the fields, compared with ambient.

Which issue(s) this PR fixes: Fixes part of #320

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

[codecov-commenter]

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[kmesh-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hzxuzhonghu

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