Support ignoring validation failures after roam.

In some scenarios, Wi-Fi connectivity is disrupted after roam. If an application reacts to network errors by calling reportNetworkConnectivity(false), validation will immediately fail and the device will switch to cell data.

Add a way to ignore these validation failures for up to 10 seconds after Wi-Fi roams.

Bug: 216567577
Test: new unit tests

Change-Id: I58de486533bcc7c6e32b23536ae15bccb779e394
diff --git a/service/ServiceConnectivityResources/res/values/overlayable.xml b/service/ServiceConnectivityResources/res/values/overlayable.xml
index 9fa6a30..b92dd08 100644
--- a/service/ServiceConnectivityResources/res/values/overlayable.xml
+++ b/service/ServiceConnectivityResources/res/values/overlayable.xml
@@ -40,6 +40,7 @@
             <item type="string" name="config_ethernet_tcp_buffers"/>
             <item type="array" name="config_ethernet_interfaces"/>
             <item type="string" name="config_ethernet_iface_regex"/>
+            <item type="integer" name="config_validationFailureAfterRoamIgnoreTimeMillis" />
         </policy>
     </overlayable>
 </resources>