Add Fairland Mr.Pure salt chlorinator alternative product (#4321)

* Add Fairland Mr.Pure

* feat (mrpure_saltchlorinator) mark missing dps as optional

Log in screenshot on PR #4321 shows a gap between 113 and 119.
Mark sensors in this range as optional.

---------

Co-authored-by: Jason Rumney <make-all@users.noreply.github.com>

custom_components/tuya_local/devices/mrpure_saltchlorinator.yaml

@@ -3,6 +3,9 @@ products:
   - id: yvsy0qxx6wboxoyh
     manufacturer: Aquark
     model: Mr.Pure
+  - id: 5ls2jw49hpczwqng
+    manufacturer: Fairland
+    model: Mr.Pure
 entities:
   - entity: sensor
     name: Salinity
@@ -156,6 +159,7 @@ entities:
     dps:
       - id: 114
         type: boolean
+        optional: true
         name: sensor
         mapping:
           - dps_val: true
@@ -168,6 +172,7 @@ entities:
     dps:
       - id: 115
         type: boolean
+        optional: true
         name: sensor
         mapping:
           - dps_val: true
@@ -180,6 +185,7 @@ entities:
     dps:
       - id: 116
         type: boolean
+        optional: true
         name: sensor
         mapping:
           - dps_val: true
@@ -192,6 +198,7 @@ entities:
     dps:
       - id: 117
         type: boolean
+        optional: true
         name: sensor
         mapping:
           - dps_val: true