dmctl: add replace command

The replace command is used to substitute the current table of a
device-mapper with the provided one.
The new table will be available as soon as the command returns
successfully.

Bug: 137759376
Test: manual
Change-Id: Iaf258d9043fab3a8770702f4e1c8c0e583c81519
Signed-off-by: Alessio Balsini <balsini@google.com>