Bug 1873025 - Fix the displayed relative time for open tabs listing to match the recency sorting.r=jsudiaman,fxview-reviewers,tabbrowser-reviewers,dao

* Carry over lastAccessed times from tabs that haven't been seen/active this session.
* Use the lastSeenActive rather than lastAccessed timestamp for labeling open tabs in firefox view.

Differential Revision: https://phabricator.services.mozilla.com/D198892

browser/components/firefoxview/opentabs.mjs

@@ -1024,7 +1024,7 @@ function getTabListItems(tabs, isRecentBrowsing) {
           ? JSON.stringify({ tabTitle: tab.label })
           : null,
       tabElement: tab,
-      time: tab.lastAccessed,
+      time: tab.lastSeenActive,
       title: tab.label,
       url,
     };