NetworkRequestDialog: Exit the dialog on connect failure

Connection failure (similar to connection success) is the end of the
processng of a request. We should dismiss the dialog on connection
failure.

Bug: 158844146
Test: Manual tests - Simulate connection failure and ensure that the
dialog vanishes with a toast.

Change-Id: I625ca76298ed549dbed76d398aea0c957c9102fc

tests/robotests/src/com/android/settings/wifi/NetworkRequestDialogActivityTest.java

@@ -230,4 +230,13 @@ public class NetworkRequestDialogActivityTest {
         assertThat(mActivity.mProgressDialog).isNull();
         assertThat(mActivity.mDialogFragment).isNull();
     }
+
+    @Test
+    public void updateAccessPointList_onUserSelectionConnectFailure_shouldFinishActivity() {
+        final WifiConfiguration config = new WifiConfiguration();
+        config.SSID = "Test AP 3";
+        mActivity.onUserSelectionConnectFailure(config);
+
+        verify(mActivity).finish();
+    }
 }