Add logic to populate initial node identity from stake table

It was noticed that the initial list of node identities does not consider the public
keys listed in the stake table.  This can easily be demonstrated by launching the
`node-metrics` binary with `ESPRESSO_NODE_VALIDATOR_STAKE_TABLE_SOURCE_BASE_URL`
and `ESPRESSO_NODE_VALIDATOR_LEAF_STREAM_SOURCE_BASE_URL` populated, but missing
`ESPRESSO_NODE_VALIDATOR_INITIAL_NODE_PUBLIC_BASE_URLS`.

In this case the list of node identities will be empty, and the information coming down
to consuming clients will be missing all node identities.

The fix is to modify the `DataState` structure so that it is initially populated with
information from the passed in stake table.

node-metrics/src/api/node_validator/v0/create_node_validator_api.rs

@@ -294,12 +294,7 @@ pub async fn create_node_validator_processing(
         .await
         .map_err(CreateNodeValidatorProcessingError::FailedToGetStakeTable)?;
 
-    let data_state = DataState::new(
-        Default::default(),
-        Default::default(),
-        stake_table,
-        Default::default(),
-    );
+    let data_state = DataState::new(Default::default(), Default::default(), stake_table);
 
     let data_state = Arc::new(RwLock::new(data_state));
     let client_thread_state = Arc::new(RwLock::new(client_thread_state));

node-metrics/src/service/data_state/mod.rs

@@ -46,8 +46,17 @@ impl DataState {
         latest_blocks: CircularBuffer<MAX_HISTORY, BlockDetail<SeqTypes>>,
         latest_voters: CircularBuffer<MAX_HISTORY, BitVec<u16>>,
         stake_table: StakeTable<BLSPubKey, StateVerKey, CircuitField>,
-        node_identity: Vec<NodeIdentity>,
     ) -> Self {
+        let node_identity = {
+            let stake_table_iter_result = stake_table.try_iter(SnapshotVersion::Head);
+            match stake_table_iter_result {
+                Ok(into_iter) => into_iter
+                    .map(|(key, _, _)| NodeIdentity::from_public_key(key))
+                    .collect(),
+                Err(_) => vec![],
+            }
+        };
+
         Self {
             latest_blocks,
             latest_voters,