add prometheus service widget

src/widgets/prometheus/widget.js

@@ -0,0 +1,14 @@
+import genericProxyHandler from "utils/proxy/handlers/generic";
+
+const widget = {
+  api: "{url}/api/v1/{endpoint}",
+  proxyHandler: genericProxyHandler,
+
+  mappings: {
+    targets: {
+      endpoint: "targets"
+    },
+  },
+};
+
+export default widget;