smartplugv2_energyv3: mark some attributes optional

To improve compatibility, mark the timers and inching (which are all too
complex to properly support) as optional.  Others with entities assigned are
left unmarked, as there are other configs that might start to conflict.

custom_components/tuya_local/devices/smartplugv2_energyv3.yaml

@@ -20,12 +20,15 @@ primary_entity:
     - id: 42
       type: base64
       name: cycle_timer
+      optional: true
     - id: 43
       type: base64
       name: random_timer
+      optional: true
     - id: 44
       type: base64
       name: inching
+      optional: true
 secondary_entities:
   - entity: number
     category: config