m/n/core/cluster: rewrite bootstrap to conform to cluster lifecycle DD

This removes the existing cluster/manager code and reimplements it from
scratch, finally implementing the cluster lifecycle design document for
cluster bootstrap.

Test Plan:
E2e should cover this. Maybe we could unit test the manager? But that would
require a ton of DI work. Not sure if it's worth it.

X-Origin-Diff: phab/D735
GitOrigin-RevId: b00c97b0a102a21605d16086df82a6ece6eb7f4d
diff --git a/metropolis/node/core/cluster/cluster.go b/metropolis/node/core/cluster/cluster.go
new file mode 100644
index 0000000..1277c2a
--- /dev/null
+++ b/metropolis/node/core/cluster/cluster.go
@@ -0,0 +1,63 @@
+// Copyright 2020 The Monogon Project Authors.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package cluster
+
+import (
+	"fmt"
+
+	"source.monogon.dev/metropolis/pkg/pki"
+)
+
+type ClusterState int
+
+const (
+	ClusterUnknown ClusterState = iota
+	ClusterForeign
+	ClusterTrusted
+	ClusterHome
+	ClusterDisowning
+)
+
+type Cluster struct {
+	State ClusterState
+}
+
+func (s ClusterState) String() string {
+	switch s {
+	case ClusterForeign:
+		return "ClusterForeign"
+	case ClusterTrusted:
+		return "ClusterTrusted"
+	case ClusterHome:
+		return "ClusterHome"
+	case ClusterDisowning:
+		return "ClusterDisowning"
+	}
+	return fmt.Sprintf("Invalid(%d)", s)
+}
+
+var clusterStateTransitions = map[ClusterState][]ClusterState{
+	ClusterUnknown: {ClusterForeign, ClusterHome, ClusterDisowning},
+	ClusterForeign: {ClusterTrusted},
+	ClusterTrusted: {ClusterHome},
+	ClusterHome:    {ClusterHome, ClusterDisowning},
+}
+
+var (
+	PKINamespace = pki.Namespaced("/cluster-pki/")
+	PKICA        = PKINamespace.New(pki.SelfSigned, "cluster-ca", pki.CA("Metropolis Cluster CA"))
+)