refactor: remove BgTabHighlighted and BgTabZoomed (not used)

src/Model/Events.purs

@@ -20,8 +20,6 @@ data BackgroundEvent
   | BgTabActivated (Maybe TabId) TabId
   | BgTabAttached Tab
   | BgTabDetached TabId
-  | BgTabHighlighted
-  | BgTabZoomChanged
 
 derive instance genBackgroundEvent :: Generic BackgroundEvent _
 

src/Sidebar/Sidebar.purs

@@ -69,8 +69,6 @@ onBackgroundMsgConsumer query =
         BgTabAttached tab -> do 
           void $ query $ H.tell $ Tabs.TabAttached tab
           pure Nothing
-        BgTabHighlighted -> pure Nothing
-        BgTabZoomChanged -> pure Nothing
 
 onSidebarMsg :: Runtime.Port -> CR.Consumer SidebarEvent Aff Unit
 onSidebarMsg port =