feat(devices): add Rheem EHG water heater

Issue #6228

Timer function mapped to "Performance" operation mode, as HA water
heater does not have any timer/schedule/program option.

DEVICES.md

@@ -261,6 +261,7 @@
 - Oekoboiler RS series heat pump water heater
 - Omni X Duplex water heater
 - Powerworld PW030, PW040, PW060, PWS58330, PWS58410 air+water heat pumps
+- Rheem EHG water heater
 - Rinnai Enviroflo heat pump water heater
 - Sanden GAU-A45HPD WiFi heat pump controller
 - Shuangri SR223 solar water heating controller

custom_components/tuya_local/devices/rheem_ehg_waterheater.yaml

@@ -0,0 +1,99 @@
+name: Water heater
+products:
+  - id: nkclmliibkaygjd9
+    manufacturer: Rheem
+    model: EHG
+entities:
+  - entity: water_heater
+    dps:
+      - id: 1
+        type: boolean
+        name: operating_mode
+        mapping:
+          - dps_val: false
+            value: "off"
+          - dps_val: true
+            constraint: mode
+            conditions:
+              - dps_val: ECO_SMART
+                value: eco
+              - dps_val: STD
+                value: electric
+              - dps_val: TIMER
+                value: performance
+      - id: 2
+        type: integer
+        name: temperature
+        unit: C
+        range:
+          min: 30
+          max: 75
+      - id: 3
+        type: integer
+        name: current_temperature
+      - id: 4
+        type: string
+        name: mode
+        hidden: true
+      - id: 101
+        type: string
+        name: away_mode
+        mapping:
+          - dps_val: "CLOSE"
+            value: false
+          - dps_val: "OPEN"
+            value: true
+  - entity: binary_sensor
+    class: running
+    dps:
+      - id: 5
+        type: string
+        name: sensor
+        mapping:
+          - dps_val: "1"
+            value: false
+          - dps_val: "2"
+            value: true
+  - entity: binary_sensor
+    class: problem
+    category: diagnostic
+    dps:
+      - id: 9
+        type: bitfield
+        name: sensor
+        mapping:
+          - dps_val: 0
+            value: false
+          - value: true
+      - id: 9
+        type: bitfield
+        name: fault_code
+      - id: 104
+        type: boolean
+        name: unknown_104
+  - entity: number
+    name: Start time
+    category: config
+    class: duration
+    icon: "mdi:clock-start"
+    dps:
+      - id: 102
+        type: integer
+        name: value
+        unit: h
+        range:
+          min: 0
+          max: 23
+  - entity: number
+    name: End time
+    category: config
+    class: duration
+    icon: "mdi:clock-end"
+    dps:
+      - id: 103
+        type: integer
+        name: value
+        unit: h
+        range:
+          min: 0
+          max: 23