LibWebView+WebContent: Add a command-line flag to disable site isolation

Author: https://github.com/trflynn89
Commit: fce5d24e5f
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/3909
Reviewed-by: https://github.com/tcl3 ✅

Libraries/LibWebView/SiteIsolation.h

@@ -10,6 +10,7 @@
 
 namespace WebView {
 
+void disable_site_isolation();
 [[nodiscard]] bool is_url_suitable_for_same_process_navigation(URL::URL const& current_url, URL::URL const& target_url);
 
 }