Followup for #13013

- The `sdcard.transfer_port` variable is Marlin's internal serial port index, not the physical serial port number.
- Added packet number to "ok" response so hosts don't need to wait for the ACK.
- Renamed feature to `BINARY_FILE_TRANSFER`, as the speed up is only consequential to the ability to transfer binaries over serial.

If in card-saving mode generate errors line errors for anything that's *NOT* "M29 ?"

* Make CardReader a static class
* Make CardReader flags into bitfields

- Remove `print_job_timer.stop()` from `disable_all_heaters`
- Call `print_job_timer.stop()` for relevant `disable_all_heaters()`.
- Split up `kill()` for watchdog interrupt safety

Co-Authored-By: Giuliano Zaro <gmagician@users.noreply.github.com>