LibWebView: Change the DevTools server to be a runtime-enabled feature

Author: https://github.com/trflynn89
Commit: df7917d705
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/3956

Libraries/LibWebView/Application.h

@@ -62,6 +62,11 @@ public:
 
     ErrorOr<LexicalPath> path_for_downloaded_file(StringView file) const;
 
+    enum class DevtoolsState {
+        Disabled,
+        Enabled,
+    };
+    ErrorOr<DevtoolsState> toggle_devtools_enabled();
     void refresh_tab_list();
 
 protected: