Add pending and failed states for admin delete.

app/src/main/protowire/Database.proto

@@ -536,6 +536,7 @@ message MessageExtras {
         PaymentTombstone paymentTombstone = 4;
         PollTerminate pollTerminate = 5;
         PinnedMessage pinnedMessage = 6;
+        AdminDeleteStatus adminDeleteStatus = 7;
     }
 }
 
@@ -550,6 +551,15 @@ message PaymentTombstone {
     CryptoValue fee = 3;
 }
 
+message AdminDeleteStatus {
+    enum Status {
+        PENDING = 0;
+        DONE = 1;
+        FAILED = 2;
+    }
+    Status status = 1;
+}
+
 message PollTerminate {
     string question = 1;
     uint64 messageId = 2;