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

cmd/bitrot_test.go

@@ -34,7 +34,7 @@ func testBitrotReaderWriterAlgo(t *testing.T, bitrotAlgo BitrotAlgorithm) {
 	volume := "testvol"
 	filePath := "testfile"
 
-	disk, err := newPosix(tmpDir, "")
+	disk, err := newXLStorage(tmpDir, "")
 	if err != nil {
 		t.Fatal(err)
 	}