m/node/allocs: split new package off m/node

The metropolis/node package contains various unrelated things. One of
these things are node-wide allocations of identifiers.
These are moved here to the new metropolis/node/allocs package.
Additionally, the constants are renamed to move the type of identifier
in front.

Change-Id: Ibc841ca64d4450a7054463e6d2d44753a118e07a
Reviewed-on: https://review.monogon.dev/c/monogon/+/4566
Reviewed-by: Tim Windelschmidt <tim@monogon.tech>
Tested-by: Jenkins CI
diff --git a/third_party/com_k8s_io_kubernetes/k8s-reserve-metropolis-ports.patch b/third_party/com_k8s_io_kubernetes/k8s-reserve-metropolis-ports.patch
index 2900867..00e4329 100644
--- a/third_party/com_k8s_io_kubernetes/k8s-reserve-metropolis-ports.patch
+++ b/third_party/com_k8s_io_kubernetes/k8s-reserve-metropolis-ports.patch
@@ -15,7 +15,7 @@
  	"sync"
  	"time"
  
-+	"source.monogon.dev/metropolis/node"
++	"source.monogon.dev/metropolis/node/allocs"
 +
  	corev1 "k8s.io/api/core/v1"
  	"k8s.io/apimachinery/pkg/api/errors"
@@ -26,7 +26,7 @@
  	}
 +
 +	// pretend that metropolis system ports are in use by an actual service
-+	for _, p := range node.SystemPorts {
++	for _, p := range allocs.SystemPorts {
 +		if err := rebuilt.Allocate(int(p)); err != nil {
 +			return fmt.Errorf("unable to allocate metropolis port: %v", err)
 +		}