Support bucket versioning (#9377)

- Implement a new xl.json 2.0.0 format to support,
  this moves the entire marshaling logic to POSIX
  layer, top layer always consumes a common FileInfo
  construct which simplifies the metadata reads.
- Implement list object versions
- Migrate to siphash from crchash for new deployments
  for object placements.

Fixes #2111

docs/bucket/versioning/xl-meta-to-json.go

@@ -0,0 +1,36 @@
+package main
+
+import (
+	"io"
+	"os"
+
+	"github.com/minio/cli"
+	"github.com/tinylib/msgp/msgp"
+)
+
+func main() {
+	app := cli.NewApp()
+	app.Copyright = "MinIO, Inc."
+	app.Usage = "xl.meta to JSON"
+	app.Version = "0.0.1"
+	app.HideHelpCommand = true
+
+	app.Flags = []cli.Flag{
+		cli.StringFlag{
+			Usage: "path to xl.meta file",
+			Name:  "f, file",
+		},
+	}
+
+	app.Action = func(c *cli.Context) error {
+		r, err := os.Open(c.String("file"))
+		if err != nil {
+			return err
+		}
+		r.Seek(8, io.SeekStart)
+		defer r.Close()
+		_, err = msgp.CopyToJSON(os.Stdout, r)
+		return err
+	}
+	app.Run(os.Args)
+}