Revert "Remove /api/client/seen-toggles as we don't need it anyway"

This reverts commit 63e6931265.

lib/routes/metrics.js

@@ -20,6 +20,23 @@ module.exports = function (app, config) {
         res.json(seenAppToggles);
     });
 
+    app.get('/client/seen-apps', (req, res) => {
+        const seenApps = metrics.getSeenAppsPerToggle();
+        clientApplicationsStore.getApplications()
+            .then(toLookup)
+            .then(metaData => {
+                Object.keys(seenApps).forEach(key => {
+                    seenApps[key] = seenApps[key].map(entry => {
+                        if (metaData[entry.appName]) {
+                            entry.data = metaData[entry.appName];
+                        }
+                        return entry;
+                    });
+                });
+                res.json(seenApps);
+            });
+    });
+
     app.get('/client/metrics/feature-toggles', (req, res) => {
         res.json(metrics.getTogglesMetrics());
     });
@@ -91,6 +108,13 @@ module.exports = function (app, config) {
             });
     });
 
+    function toLookup (metaData) {
+        return metaData.reduce((result, entry) => {
+            result[entry.appName] = entry;
+            return result;
+        }, {});
+    }
+
     app.get('/client/applications/', (req, res) => {
         clientApplicationsStore
             .getApplications(req.query)