Browser+LibWeb+WebContent: Add action to clear resource cache

Author: https://github.com/trflynn89
Commit: 855920fe13
Pull-request: https://github.com/SerenityOS/serenity/pull/6017

Userland/Libraries/LibWeb/Loader/ResourceLoader.cpp

@@ -236,4 +236,10 @@ bool ResourceLoader::is_port_blocked(int port)
     return false;
 }
 
+void ResourceLoader::clear_cache()
+{
+    dbgln("Clearing {} items from ResourceLoader cache", s_resource_cache.size());
+    s_resource_cache.clear();
+}
+
 }