feat(config): support openmetrics by allowed clients

Signed-off-by: WrenIX <133280015+wrenix@users.noreply.github.com>

.config/openmetrics.config.php

@@ -0,0 +1,6 @@
+<?php
+
+$openmetricsAllowedClients = getenv('OPENMETRICS_ALLOWED_CLIENTS');
+if ($openmetricsAllowedClients) {
+  $CONFIG['openmetrics_allowed_clients'] = array_filter(array_map('trim', explode(',', $openmetricsAllowedClients)));
+}