BVP CP-1: add hvac_action dp

- make naming follow modern convention (branding under products)
- although report does not use optional, it was not in the original
  request #425, though there was no log provided then, so no way to know
  for sure whether it needs to be optional or not.

Issue #1977

custom_components/tuya_local/devices/bvf_cp1_heater.yaml

@@ -1,6 +1,7 @@
-name: BVF CP-1 heater
+name: Heater
 products:
   - id: t2htqaryl4gymeuv
+    name: BVP CP-1
 primary_entity:
   entity: climate
   translation_only_key: heater
@@ -25,6 +26,21 @@ primary_entity:
           value: away
         - dps_val: auto
           value: home
+    - id: 3
+      type: string
+      optional: true
+      name: hvac_action
+      mapping:
+        - constraint: hvac_mode
+          conditions:
+            - dps_val: false
+              value: "off"
+            - dps_val: true
+              mapping:
+                - dps_val: heating
+                  value: heating
+                - dps_val: standby
+                  value: idle
     - id: 16
       type: integer
       name: temperature