Add method that checks the Binder status of ImsConfig

Adds a method to check whether or not the ImsConfig
binder has died.

Bug: 62723694
Test: maual, follow bug procedure
Change-Id: I9df6533e7e7dc69487cea50fada6c89599b031a3

telephony/java/com/android/ims/ImsConfig.java

@@ -697,4 +697,11 @@ public class ImsConfig {
                     ImsReasonInfo.CODE_LOCAL_SERVICE_UNAVAILABLE);
         }
     }
+
+    /**
+     * @return true if the binder connection is alive, false otherwise.
+     */
+    public boolean isBinderAlive() {
+        return miConfig.asBinder().isBinderAlive();
+    }
 }