r/v-m: Add role for Victoria Metrics

The *victoria-metrics* role deploys a single-server instance of the
Victoria Metrics time series database server.  It installs the selected
version by downloading the binary release from Github and copying it to
`/usr/local/sbin` on the managed node.  Scrape configuration is optional
and can be specified with the `scrape_configs` variable.

roles/victoria-metrics/handlers/main.yml

@@ -0,0 +1,14 @@
+- name: reload systemd
+  systemd:
+    daemon_reload: true
+
+- name: restart victoria-metrics
+  service:
+    name: victoria-metrics
+    state: restarted
+
+- name: reload victoria-metrics
+  uri:
+    url: http://localhost:8428/-/reload
+    status_code: 204
+  changed_when: true