[ACA-1695] viewer extensions (#576)

[ACA-1695] viewer extensions

extension.schema.json

@@ -268,6 +268,32 @@
                     }
                 }
             }
+        },
+        "viewerExtensionRef": {
+            "type": "object",
+            "required": ["id", "component", "fileExtension"],
+            "properties": {
+                "id": {
+                    "description": "Unique identifier for the navigation group",
+                    "type": "string"
+                },
+                "component": {
+                    "description": "Component id",
+                    "type": "string"
+                },
+                "fileExtension": {
+                    "description": "Target file extension",
+                    "type": "string"
+                },
+                "order": {
+                    "description": "Group order",
+                    "type": "number"
+                },
+                "disabled": {
+                    "description": "Toggles the disabled state",
+                    "type": "boolean"
+                }
+            }
         }
     },
 
@@ -337,6 +363,12 @@
                             "type": "array",
                             "items": { "$ref": "#/definitions/contentActionRef" },
                             "minItems": 1
+                        },
+                        "content": {
+                            "description": "Viewer content extensions",
+                            "type": "array",
+                            "items": { "$ref": "#/definitions/viewerExtensionRef" },
+                            "minItems": 1
                         }
                     }
                 },