grafana: Deploy Grafana

Now that Victoria Metrics is hosted in Kubernetes, it only makes sense
to host Grafana there as well.  I chose to use a single-instance
deployment for simplicity; I don't really need high availability for
Grafana.  Its configuration does not change enough to worry about the
downtime associated with restarting it.  Migrating the existing data
from SQLite to PostgreSQL, while possible, is just not worth the hassle.

argocd/applications/grafana.yaml

@@ -0,0 +1,13 @@
+apiVersion: argoproj.io/v1alpha1
+kind: Application
+metadata:
+  name: grafana
+  namespace: argocd
+spec:
+  destination:
+    server: https://kubernetes.default.svc
+  project: default
+  source:
+    path: grafana
+    repoURL: https://git.pyrocufflink.blue/infra/kubernetes.git
+    targetRevision: master