feat(moebot_s_mower): Add Backward Blade Stop

This was added by a recent firmware upgrade.

custom_components/tuya_local/devices/moebot_s_mower.yaml

@@ -306,3 +306,17 @@ entities:
         type: boolean
         name: switch
         optional: true
+  - entity: switch
+    name: Backward Blade Stop
+    icon: "mdi:saw-blade"
+    category: config
+    dps:
+      - id: 121
+        type: integer
+        name: switch
+        optional: true
+        mapping:
+          - dps_val: 0
+            value: false
+          - dps_val: 1
+            value: true