Only clear the selection if the selection needs to change. (#689)

Task/Issue URL: https://app.asana.com/0/1199230911884351/1202801432128120/f
Tech Design URL:
CC:

Description:

This PR fixes an issue where tabs opened in the background would cause the current tab selection to be cleared.

DuckDuckGo/Tab Bar/View/TabBarViewController.swift

@@ -687,7 +687,10 @@ extension TabBarViewController: TabCollectionViewModelDelegate {
         }
         updateTabMode(for: collectionView.numberOfItems(inSection: 0) + 1)
 
-        collectionView.clearSelection()
+        if selected {
+            collectionView.clearSelection()
+        }
+
         if tabMode == .divided {
             collectionView.animator().insertItems(at: lastIndexPathSet)
             if selected {