Add "blockedDetails" section to troubleshooting information

This will allow to find out what is specifically blocked on the
page reported as having issues, potentially saving time
when volunteers try to diagnose issues.

src/js/popup-fenix.js

@@ -856,6 +856,19 @@ const gotoReport = function() {
         if ( popupData[prop] === expected ) { continue; }
         popupPanel[name] = !expected;
     }
+    if ( hostnameToSortableTokenMap.size !== 0 ) {
+        const blockedDetails = {};
+        const hostnames =
+            Array.from(hostnameToSortableTokenMap.keys()).sort(hostnameCompare);
+        for ( const hostname of hostnames ) {
+            const entry = popupData.hostnameDict[hostname];
+            if ( entry.counts.blocked.any === 0 ) { continue; }
+            blockedDetails[hostname] = entry.counts.blocked.any;
+        }
+        if ( Object.keys(blockedDetails).length !== 0 ) {
+            popupPanel.blockedDetails = blockedDetails;
+        }
+    }
     messaging.send('popupPanel', {
         what: 'launchReporter',
         tabId: popupData.tabId,