feat: enable plugins for grafana (#378)

- add method to install plugins for grafana
- ensure victoriametrics-logs-datasource is installed

Reviewed-on: #378

site/profiles/manifests/metrics/grafana.pp

@@ -11,6 +11,7 @@ class profiles::metrics::grafana (
   String    $db_pass     = fqdn_rand_string(16),
   Stdlib::Host $db_host  = '127.0.0.1',
   Stdlib::Port $db_port  = 5432,
+  Hash      $plugins     = {}
 ) {
 
   # set the fqdn
@@ -108,6 +109,7 @@ class profiles::metrics::grafana (
   class { 'grafana':
     cfg      => $cfg,
     ldap_cfg => $ldap_cfg,
+    plugins  => $plugins,
   }
 
   # fix the package provided systemd service