Add UHM-M collection support to FeedServe.

Tested via:
```
$ blaze run //platforms/syshealth/collection/feed/serve:main -- --alsologtostderr --collector_menu_override='
        collectibles {
          policy_id: "UhmmCtqNodePortsFromMachineV2"
          agent_identifier { agent_type: AGENT_TYPE_UHMM }
          source {
            uhmm_source {
              canned_table_query {
                canned_table_query_name: UHMM_CTQ_NODE_PORTS_FROM_MACHINE_V2
                model_view {
                  model_class: MC_UHM_MACHINE
                  model_stage: STAGE_ASMAINTAINED
                  profile_version {
                    profile_version_number { major: 1 minor: 0 }
                  }
                }
              }
            }
          }
          output_configs {
            destination: DESTINATION_HDB
            hdb_output {}
          }
        }
'
```

Then a local query via:

```
$ stubby call localhost:7777 FeedServe.CollectForPolicyIds 'entity { type: MACHINE name: "efa1" metadata { hostname: "efa1" }} policy_id: "UhmmCtqNodePortsFromMachineV2"'
```

Output: https://paste.googleplex.com/5355472068673536?raw
PiperOrigin-RevId: 822762103
Change-Id: I9a1ad55f95d95ed17e3d9f14e6d61ccc71b1e984
diff --git a/tlbmc/service_messages.proto b/tlbmc/service_messages.proto
index d1e8235..ea1ee0a 100644
--- a/tlbmc/service_messages.proto
+++ b/tlbmc/service_messages.proto
@@ -31,6 +31,7 @@
     AGENT_TYPE_BMCWEB = 2;
     AGENT_TYPE_GSYS = 3;
     AGENT_TYPE_PICTOR = 4;
+    AGENT_TYPE_UHMM = 5;
     // Add more agent types here.
   }
   optional AgentType agent_type = 1;