Prometheus: Create jsonschema spec (#85077)

pkg/promlib/models/query.request.example.json

@@ -0,0 +1,12 @@
+{
+  "from": "now-1h",
+  "to": "now",
+  "queries": [
+    {
+      "refId": "A",
+      "maxDataPoints": 1000,
+      "intervalMs": 5,
+      "expr": "1+1"
+    }
+  ]
+}