Reset the service hours warnings

[tiagofreire-pt]

After enabling the printcounter:

  #define SERVICE_WARNING_BUZZES  3
  // Activate up to 3 service interval watchdogs
  #define SERVICE_NAME_1      "Service > 100h"
  #define SERVICE_INTERVAL_1  100 // print hours
  #define SERVICE_NAME_2      "Service > 200h"
  #define SERVICE_INTERVAL_2  200 // print hours
  #define SERVICE_NAME_3      "Service 3 > 300h"
  #define SERVICE_INTERVAL_3  300 // print hours
#endif

This definition will always warn about the due to maintenance. But it is not possible to reset it from the printer UI.

I wonder if the M78 g-code is the solution to this issue, lacking any documentation: https://marlinfw.org/docs/gcode/M078.html

Would be awesome to reset this through the UI, Control--> Info -> Reset maintenance counter

[tiagofreire-pt]

Done: d0f203d

See: #1579