LibWeb+LibWebView+WebContent: Add an Inspector IPC to execute JavaScript

The Inspector will have an <input> element to execute user-provided JS.
This adds an IDL method and IPC to forward that JS from the Inspector
WebView to the Inspector client.

Userland/Libraries/LibWeb/Internals/Inspector.h

@@ -21,6 +21,8 @@ public:
     void inspector_loaded();
     void inspect_dom_node(i32 node_id, Optional<i32> const& pseudo_element);
 
+    void execute_console_script(String const& script);
+
 private:
     explicit Inspector(JS::Realm&);