Update schema with the Icon device property. (#7018)

* Device-specific icon

* Updated tests.

* Updated test

* Updated tests

* Updated tests.

* Updated tests

* Update schema with the Icon device property.

* Fix

Co-authored-by: ptvoinfo <xagga@ya.ru>

lib/util/settings.schema.json

@@ -702,6 +702,11 @@
           "examples": ["temperature", "battery", "action"],
           "title": "Filtered attributes",
           "description": "Allows to prevent certain attributes from being published"
+        },
+        "icon": {
+          "type": "string",
+          "title": "Icon",
+          "description": "The user-defined device icon for the frontend. It can be a link to an image (not a path to a file) or base64 encoded data URL like: image/svg+xml;base64,PHN2ZyB3aW....R0aD"
         }
       },
       "required": ["friendly_name"]