UI: Add an option to enable autoplay globally

Author: https://github.com/tcl3
Commit: 63632159ce
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/1497
Reviewed-by: https://github.com/trflynn89

Userland/Libraries/LibWebView/ViewImplementation.h

@@ -73,6 +73,8 @@ public:
 
     void set_enable_do_not_track(bool);
 
+    void set_enable_autoplay(bool);
+
     ByteString selected_text();
     Optional<String> selected_text_with_whitespace_collapsed();
     void select_all();