Wifi watchdog feature overlay

Add OEM feature overlay for this feature.
Enabled by default.

Bug: 143540634
Test: frameworks/opt/net/wifi/tests/wifitests/runtests.sh -e class com.android.server.wifi.WifiLastResortWatchdogTest
      OK (43 tests)
Test: flash device with the default value (true) and config can be
      overwrite by overlay.

Change-Id: I6fdcbdcf742acece3aa5d4a415946f7c98c98bfe
diff --git a/service/res/values/config.xml b/service/res/values/config.xml
index 0b36232..3cc44ba 100644
--- a/service/res/values/config.xml
+++ b/service/res/values/config.xml
@@ -225,4 +225,7 @@
 
     <!-- Indicates that a full bugreport should be triggered when wifi diagnostics detects an error on non-user (i.e debug) builds -->
     <bool translatable="false" name="config_wifi_diagnostics_bugreport_enabled">false</bool>
+
+    <!-- Indicates that wifi watchdog is enabled on this device -->
+    <bool translatable="false" name="config_wifi_watchdog_enabled">true</bool>
 </resources>