Clean air dehumidifier: merge fan into humidifier

A fan with just a switch is not really useful, so move the switch to
the humidifier entity, and move the switching of dehumidifier/purifier to
the mode.

Issue #2680

custom_components/tuya_local/devices/cleanair_ca702_dehumidifier.yaml

@@ -4,25 +4,20 @@ products:
     manufacturer: Clean Air Optima
     model: CA-702 Smart
 entities:
-  - entity: fan
-    dps:
-      - id: 1
-        type: boolean
-        name: switch
   - entity: humidifier
     class: dehumidifier
     dps:
       - id: 1
         type: boolean
-        name: available
+        name: switch
       - id: 2
         type: string
-        name: switch
+        name: mode
         mapping:
           - dps_val: auto
-            value: true
+            value: auto
           - dps_val: fan
-            value: false
+            value: purify
       - id: 3
         type: integer
         name: current_humidity