improve no camera view

instead of showing an "add camera" message, show a specific message for empty camera groups when frigate already has cameras added

web/public/locales/en/views/live.json

@@ -181,6 +181,16 @@
     "restricted": {
       "title": "No Cameras Available",
       "description": "You don't have permission to view any cameras in this group."
+    },
+    "default": {
+      "title": "No Cameras Configured",
+      "description": "Get started by connecting a camera to Frigate.",
+      "buttonText": "Add Camera"
+    },
+    "group": {
+      "title": "No Cameras in Group",
+      "description": "This camera group has no assigned or enabled cameras.",
+      "buttonText": "Manage Groups"
     }
   }
 }