IP connectivity metrics: ConnectStats additions

This patch:
  - adds a counter to ConnectStats for counting the number of successful
    connect() calls done in blocking mode. This allows to compute error
    rates for connect() in blocking mode.
  - add printing of ConnectStats when dumping NetdEventListenerService
    and/or IpConnectivityMetrics service.

Test: $ runtest frameworks-net, + manual tests verifying logged events.
Bug: 34901696
Change-Id: I889e8ccd12681b0511be487e9d2ee44290a2d7d7
diff --git a/services/core/java/com/android/server/connectivity/IpConnectivityMetrics.java b/services/core/java/com/android/server/connectivity/IpConnectivityMetrics.java
index 445f606..da56a07 100644
--- a/services/core/java/com/android/server/connectivity/IpConnectivityMetrics.java
+++ b/services/core/java/com/android/server/connectivity/IpConnectivityMetrics.java
@@ -201,12 +201,18 @@
             for (IpConnectivityEvent ev : IpConnectivityEventBuilder.toProto(events)) {
                 pw.print(ev.toString());
             }
+            if (mNetdListener != null) {
+                mNetdListener.listAsProtos(pw);
+            }
             return;
         }
 
         for (ConnectivityMetricsEvent ev : events) {
             pw.println(ev.toString());
         }
+        if (mNetdListener != null) {
+            mNetdListener.list(pw);
+        }
     }
 
     private void cmdStats(FileDescriptor fd, PrintWriter pw, String[] args) {