[reconfigurator] rot-bootloader subcommand for reconfigurator-sp-updater

[karencfv]

This won't really do anything until #8325 is merged. But will be good having this around for performing manual tests,

$ ./target/debug/reconfigurator-sp-updater --dns-server [::1]:47679 [::]:34643
Jun 13 01:13:02.664 INFO setting up resolver
Jun 13 01:13:02.664 INFO resolve MGS in DNS
Jun 13 01:13:02.720 INFO loaded inventory from MGS
Jun 13 01:13:02.720 INFO starting MgsUpdateDriver
〉help set
Configure an update

Usage: set <SERIAL> <ARTIFACT_HASH> <VERSION> <COMMAND>

Commands:
  sp              
  rot             
  rot-bootloader  
  help            Print this message or the help of the given subcommand(s)

Arguments:
  <SERIAL>         serial number to update
  <ARTIFACT_HASH>  artifact hash id
  <VERSION>        version

Options:
  -h, --help  Print help
〉help set rot-bootloader
Usage: set <SERIAL> <ARTIFACT_HASH> <VERSION> rot-bootloader --expected-stage0-version <EXPECTED_STAGE0_VERSION> --expected-stage0-next-version <EXPECTED_STAGE0_NEXT_VERSION>

Options:
  -a, --expected-stage0-version <EXPECTED_STAGE0_VERSION>            expected version of the active slot
  -i, --expected-stage0-next-version <EXPECTED_STAGE0_NEXT_VERSION>  expected version of the inactive slot
  -h, --help                                                         Print help
〉

Related: #7988