machine: use new internal/binary package

The encoding/binary package in Go 1.23 imports the slices package, which
results in circular import when imported from the machine package.
Therefore, encoding/binary cannot be used in the machine package.

This commit fixes that by introducing a new internal/binary package that
is just plain Go code without dependencies. It can be safely used
anywhere (including the runtime if needed).

src/machine/machine_nrf.go

@@ -5,7 +5,7 @@ package machine
 import (
 	"bytes"
 	"device/nrf"
-	"encoding/binary"
+	"internal/binary"
 	"runtime/interrupt"
 	"unsafe"
 )