LibWeb/CSP: Implement the connect-src directive

Author: https://github.com/Lubrsi
Commit: 959bb5cc18
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/5276
Reviewed-by: https://github.com/shannonbooth ✅

Libraries/LibWeb/Forward.h

@@ -130,6 +130,7 @@ struct SerializedPolicy;
 
 namespace Web::ContentSecurityPolicy::Directives {
 
+class ConnectSourceDirective;
 class Directive;
 struct SerializedDirective;