Fixes the firing of mh pixel (#2503)

Task/Issue URL: https://app.asana.com/0/414709148257752/1206674614649925/f
Tech Design URL:
CC:

Description:
Fixes the firing of mh pixel

Steps to test this PR:

Launch the app, ensure mh pixel is fired when the the new tab is shown
Create tabs from the tab switcher.  mh should only be fired when the the user ends up on the Home Screen
Check RMF message still displays as expected

DuckDuckGo/HomeViewController.swift

@@ -264,12 +264,14 @@ class HomeViewController: UIViewController {
 
     override func viewDidAppear(_ animated: Bool) {
         super.viewDidAppear(animated)
-        
-        if presentedViewController == nil { // prevents these being called when settings forces this controller to be reattached
-            showNextDaxDialog()
-        }
+
+        // If there's no tab switcher then this will be true, if there is a tabswitcher then only allow the
+        //  stuff below to happen if it's being dismissed
+        guard presentedViewController?.isBeingDismissed ?? true else { return }
 
         Pixel.fire(pixel: .homeScreenShown)
+        showNextDaxDialog()
+
         collectionView.didAppear()
 
         viewHasAppeared = true

DuckDuckGo/MainViewController.swift

@@ -2058,8 +2058,12 @@ extension MainViewController: TabSwitcherDelegate {
     func tabSwitcher(_ tabSwitcher: TabSwitcherViewController, didRemoveTab tab: Tab) {
         if tabManager.count == 1 {
             // Make sure UI updates finish before dimissing the view.
+            // However, as a result, viewDidAppear on the home controller thinks the tab 
+            //  switcher is still presented.
             DispatchQueue.main.asyncAfter(deadline: .now() + 0.2) {
-                tabSwitcher.dismiss()
+                tabSwitcher.dismiss(animated: true) {
+                    self.homeController?.viewDidAppear(true)
+                }
             }
         }
         closeTab(tab)