cloud/shepherd: add equinix API metrics

This adds the following signals to our interaction with the Equinix API:

 1. Latency
 2. Traffic
 3. Errors
 4. Saturation

Change-Id: Ic2d5e36a7a26ab906ac1c2fa6741ebf86b9e551a
Reviewed-on: https://review.monogon.dev/c/monogon/+/1606
Tested-by: Jenkins CI
Reviewed-by: Tim Windelschmidt <tim@monogon.tech>
diff --git a/cloud/shepherd/equinix/wrapngo/BUILD.bazel b/cloud/shepherd/equinix/wrapngo/BUILD.bazel
index 166ee76..521e1ca 100644
--- a/cloud/shepherd/equinix/wrapngo/BUILD.bazel
+++ b/cloud/shepherd/equinix/wrapngo/BUILD.bazel
@@ -4,6 +4,7 @@
     name = "wrapngo",
     srcs = [
         "duct_tape.go",
+        "metrics.go",
         "wrapn.go",
     ],
     importpath = "source.monogon.dev/cloud/shepherd/equinix/wrapngo",
@@ -12,6 +13,7 @@
         "@com_github_cenkalti_backoff_v4//:backoff",
         "@com_github_google_uuid//:uuid",
         "@com_github_packethost_packngo//:packngo",
+        "@com_github_prometheus_client_golang//prometheus",
         "@io_k8s_klog_v2//:klog",
     ],
 )