add MQTT button for updating time

include/devices.h

@@ -63,6 +63,13 @@ namespace Devices {
                 }
             }).build()
         )
+        .addSecondary(
+            Builder<Button>::instance(new Button{"Update time", "update_time",
+                [](const char* msg) {
+                    if (strcmp("PRESS", msg) == 0) Ntp::tUpdateTime.restart();
+                }
+            }).build()
+        )
         .addSecondary(ledMqtt)
         .addConfiguration(brightnessMqtt)
         .addConfiguration(hourFormatMqtt)