added aks platform which is similar to gke (#1869)

jsonnet/kube-prometheus/platforms/aks.libsonnet

+(import '../addons/managed-cluster.libsonnet') + {
+  values+:: {
+    prometheusAdapter+: {
+      config+: {
+        resourceRules:: null,
+      },
+    },
+  },
+
+  prometheusAdapter+:: {
+    apiService:: null,
+  },
+}