Set OS function for QMK with update eeprom functionality

set_os.c

void set_os(OS type, bool update) {
    userspace_config.curr_os = type;
    underlight_color = HSV_COEFFICIENT * type;
    switch (type) {
        case OS_MAC:
          set_unicode_input_mode(UC_OSX_RALT);
          userspace_config.next_os = OS_WIN;
          break;

        case OS_WIN:
          set_unicode_input_mode(UC_WIN);
          userspace_config.next_os = OS_NIX;
          break;

        case OS_NIX:
          set_unicode_input_mode(UC_LNX);
          userspace_config.next_os = OS_MAC;
          break;
    }
    
    if (update) {
      rgblight_sethsv(underlight_color, 255, 255);
      eeprom_update_byte(EECONFIG_USERSPACE, userspace_config.raw);
    } else {
      rgblight_sethsv_noeeprom(underlight_color, 255, 255);
    }
}