Add ForceToUseFakeDocument option for document loading

Introduced a new `ForceToUseFakeDocument` property in `ApiOptions` to control whether the application uses a fake document for testing or bypasses certain conditions for document loading. Updated `ReportViewer.razor` to respect this configuration, including changes to conditional rendering logic and dependency injection for `IOptions<ApiOptions>`.

Removed test code that forced `EnvelopeKey` to `null` during initialization. Updated `appsettings.json` to include the new `ForceToUseFakeDocument` property with a default value of `true`. Added necessary `using` directives and dependencies for the updated functionality.

EnvelopeGenerator.ReceiverUI/wwwroot/appsettings.json

@@ -1,5 +1,6 @@
 {
   "Api": {
-    "BaseUrl": "https://localhost:8088"
+    "BaseUrl": "https://localhost:8088",
+    "ForceToUseFakeDocument": true
   }
 }