feat (avatto_wt20r_thermostat): add window open switch

Additional control found on WT20R-WH-3A-W

Issue #3905

custom_components/tuya_local/devices/avatto_wt20r_thermostat.yaml

@@ -163,3 +163,26 @@ entities:
             value: Internal
           - dps_val: out
             value: External
+  # Additional entities from WT20R variants
+  - entity: switch
+    name: Open window detection
+    category: config
+    icon: "mdi:window-open-variant"
+    hidden: unavailable
+    dps:
+      - id: 8
+        type: boolean
+        optional: true
+        name: switch
+      - id: 8
+        type: boolean
+        optional: true
+        name: available
+        mapping:
+          - dps_val: null
+            value: false
+          - value: true
+# 102/103: Holiday temperature, but range unknown
+# 104: sencer_c (sic) value "in", range unknown but probably same as 101?
+# 105/107: Home temperature, not sure if it is a setting or sensor
+# 112/113: Cook temperature, not sure what this is for (bad translation?)