Add open in app to main three dot menu (#18462)

app/src/main/java/org/mozilla/fenix/components/toolbar/DefaultToolbarMenu.kt

@@ -441,6 +441,19 @@ class DefaultToolbarMenu(
             onItemTapped.invoke(ToolbarMenu.Item.CustomizeReaderView)
         }
 
+        val openInApp = BrowserMenuHighlightableItem(
+            label = context.getString(R.string.browser_menu_open_app_link),
+            startImageResource = R.drawable.ic_open_in_app,
+            iconTintColorResource = primaryTextColor(),
+            highlight = BrowserMenuHighlight.LowPriority(
+                label = context.getString(R.string.browser_menu_open_app_link),
+                notificationTint = getColor(context, R.color.whats_new_notification_color)
+            ),
+            isHighlighted = { !context.settings().openInAppOpened }
+        ) {
+            onItemTapped.invoke(ToolbarMenu.Item.OpenInApp)
+        }
+
         val reportSiteIssuePlaceholder = WebExtensionPlaceholderMenuItem(
             id = WebCompatReporterFeature.WEBCOMPAT_REPORTER_EXTENSION_ID
         )
@@ -500,6 +513,7 @@ class DefaultToolbarMenu(
                 findInPageItem,
                 desktopSiteItem,
                 customizeReaderView.apply { visible = ::shouldShowReaderViewCustomization },
+                openInApp.apply { visible = ::shouldShowOpenInApp },
                 reportSiteIssuePlaceholder,
                 BrowserMenuDivider(),
                 addToHomeScreenItem.apply { visible = ::canAddToHomescreen },