LibWebView+UI: Generate the application debug menu

By migrating the debug menu to LibWebView, the AppKit and Qt UIs are now
in sync - the AppKit UI was previously missing some actions.

Further, this inadvertently fixes bugs around applying debug settings to
new web views, especially across site-isolated processes. We were
previously not applying settings appropriately; this now "just works" in
the LibWebView infra.

UI/AppKit/Interface/TabController.h

@@ -13,14 +13,6 @@
 
 @class Tab;
 
-struct TabSettings {
-    BOOL should_show_line_box_borders { NO };
-    BOOL scripting_enabled { YES };
-    BOOL block_popups { YES };
-    ByteString user_agent_name { "Disabled"sv };
-    ByteString navigator_compatibility_mode { "chrome"sv };
-};
-
 @interface TabController : NSWindowController <NSWindowDelegate>
 
 - (instancetype)init;
@@ -34,14 +26,8 @@ struct TabSettings {
 
 - (void)onURLChange:(URL::URL const&)url;
 
-- (void)onCreateNewTab;
-
 - (void)clearHistory;
 
-- (void)setPopupBlocking:(BOOL)block_popups;
-- (void)setScripting:(BOOL)enabled;
-- (void)debugRequest:(ByteString const&)request argument:(ByteString const&)argument;
-
 - (void)focusLocationToolbarItem;
 
 @end