Onboard multi volume support

[kisslorand]

Requirements

• BTT or MKS TFT
• motherboard with an USB storage port
• Marlin (not older than 28.II.2022)

Description

This PR adds the ability to select USB media also from motherboards which are equipped with it

Benefits

Everyone using Marlin with motherboards that also have USB media storage port.

Related Issues

Fixes #2215

Notes

This PR is marked as draft because in Marlin there's no gcode for setting/switching the storage yet. However there's a pending PR for that on Marlin's Github repository (MarlinFirmware/Marlin#23780).
For those who still want to use this feature here's what is needed to be done in Marlin source code in order to be able to use this feature:

1. in "M21_M22.cpp" replace

void GcodeSuite::M21() { card.mount(); }

with

void GcodeSuite::M21()
{
  #if ENABLED(MULTI_VOLUME)
    if (parser.seen('S')) {  // "S" for SD Card
      card.changeMedia(&card.media_driver_sdcard);
    }
    else if (parser.seen('U')) {  // "U" for USB
      card.changeMedia(&card.media_driver_usbFlash);
    }
  #endif
  card.mount();
}

2. in "M155.cpp" after the lines

    // SDCARD (M20, M23, M24, etc.)
    cap_line(F("SDCARD"), ENABLED(SDSUPPORT));

add the folowing:

    // MULTI_VOLUME (M21 S/M21 U)
    #if ENABLED(SDSUPPORT)
      cap_line(F("MULTI_VOLUME"), ENABLED(MULTI_VOLUME));
    #endif

Enjoy !!!

L.E.: MarlinFirmware/Marlin#23780 has been merged so this PR is fully functional without any Marlin modification.

[Guilouz]

Tested and working fine !

[kisslorand]

Thank you for the feedback.

[kisslorand]

@bigtreetech
MarlinFirmware/Marlin#23780 has been merged so this PR is fully functional without any Marlin modification, it can be merged.