Always reset nonce on RandomX dataset change

Also never get a new job when mining is paused

src/backend/cpu/CpuWorker.cpp

@@ -359,7 +359,9 @@ void xmrig::CpuWorker<N>::start()
             }
         }
 
-        consumeJob();
+        if (!Nonce::isPaused()) {
+            consumeJob();
+        }
     }
 }