Add total RAM, CPUs and disk size to servers summary as well as disk usage in percent. Fixes https://github.com/GNS3/gns3-server/issues/1532

tests/controller/test_compute.py

@@ -292,10 +292,14 @@ async def test_json(compute):
         "user": "test",
         "cpu_usage_percent": None,
         "memory_usage_percent": None,
+        "disk_usage_percent": None,
         "connected": True,
         "last_error": None,
         "capabilities": {
             "version": None,
+            "cpus": None,
+            "memory": None,
+            "disk_size": None,
             "node_types": []
         }
     }