tsconsensus: enable writing state to disk

The comments in the raft code say to only use the InMemStore for tests.

Updates #16027

Signed-off-by: Fran Bull <fran@tailscale.com>

tsconsensus/bolt_store.go

@@ -0,0 +1,19 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+//go:build !loong64
+
+package tsconsensus
+
+import (
+	"github.com/hashicorp/raft"
+	raftboltdb "github.com/hashicorp/raft-boltdb/v2"
+)
+
+func boltStore(path string) (raft.StableStore, raft.LogStore, error) {
+	store, err := raftboltdb.NewBoltStore(path)
+	if err != nil {
+		return nil, nil, err
+	}
+	return store, store, nil
+}