LibWeb+Browser: Make ad blocking work in the multi-process world

We now send the list of content filters over to new WebContent processes
after creating an OutOfProcessWebView. :^)

Userland/Services/WebContent/WebContentServer.ipc

@@ -38,4 +38,7 @@ endpoint WebContentServer
 
     get_selected_text() => (String selection)
     select_all() =|
+
+    set_content_filters(Vector<String> filters) =|
+
 }