cloud/bmaas/bmdb: implement BMDB client metrics

This implements some basic BMDB metrics exported by any client code
using the BMDB.

It also enables their use in the Shepherd and BMSRV.

Change-Id: I1d5e82fd2c34a7bfd42f37fad540d69f7b23f347
Reviewed-on: https://review.monogon.dev/c/monogon/+/1600
Tested-by: Jenkins CI
Reviewed-by: Tim Windelschmidt <tim@monogon.tech>
diff --git a/cloud/shepherd/equinix/manager/server/main.go b/cloud/shepherd/equinix/manager/server/main.go
index 14b94bc..21e7e5a 100644
--- a/cloud/shepherd/equinix/manager/server/main.go
+++ b/cloud/shepherd/equinix/manager/server/main.go
@@ -59,6 +59,9 @@
 	c.RegisterFlags()
 	flag.Parse()
 
+	registry := c.Component.PrometheusRegistry()
+	c.BMDB.EnableMetrics(registry)
+
 	ctx := clicontext.WithInterrupt(context.Background())
 	c.Component.StartPrometheus(ctx)