Internal listener and upstream transport support

[YaoZengzeng]

To work as waypoint, orion need to support internal listener and internal upstream transport.

Ref: https://www.envoyproxy.io/docs/envoy/latest/configuration/other_features/internal_listener and https://www.envoyproxy.io/docs/envoy/latest/api-v3/extensions/transport_sockets/internal_upstream/v3/internal_upstream.proto#internal-upstream-proto

Config dump segment:

      "load_assignment": {
       "cluster_name": "encap",
       "endpoints": [
        {
         "lb_endpoints": [
          {
           "endpoint": {
            "address": {
             "envoy_internal_address": {
              "server_listener_name": "connect_originate"
....

     "transport_socket": {
       "name": "internal_upstream",
       "typed_config": {
        "@type": "type.googleapis.com/envoy.extensions.transport_sockets.internal_upstream.v3.InternalUpstreamTransport",
        "passthrough_metadata": [
         {
          "kind": {
           "host": {}
          },
          "name": "envoy.filters.listener.original_dst"
         }
        ],
        "transport_socket": {
         "name": "raw_buffer",
         "typed_config": {
          "@type": "type.googleapis.com/envoy.extensions.transport_sockets.raw_buffer.v3.RawBuffer"
         }
        }

[Eeshu-Yadav]

/assign

[Eeshu-Yadav]

Sub-Issues for completing this

1. Internal Connection Factory Implementation #105

2. Enhanced Internal Listener Runtime #106

3. Cluster Internal Connection Support #107

4. Internal Upstream Transport & Metadata Passthrough #108