Each core provides a different USBAPI

The Arduino Core API defines a very low level USB api in [api/USBAPI.h](https://github.com/arduino/ArduinoCore-API/blob/master/api/USBAPI.h). This API is implemented by the avr core in [cores/arduino/USBCore.cpp](https://github.com/arduino/ArduinoCore-avr/blob/master/cores/arduino/USBCore.cpp). But it is not implemented by samd core, which implements the same functionality but in its own [`USBDeviceClass` class](https://github.com/arduino/ArduinoCore-samd/blob/master/cores/arduino/USB/USBCore.cpp). The USB implementation in megaavr core (`USBCore.cpp`) is a copy of the avr usb implementation with some deviations. The mbed core implements its own version of the `PluggableUSBModule`.

As a result, each core implements its own USB API which is incompatible with the others, there exist many code duplicates and users of the USB API have to understand and adapt their code to each individual core implementation.

Are there any plans to improve this situation?

Commencez par api/USBAPI.h et comparez les implémentations dans les chemins de core avr, samd, megaavr et mbed mentionnés dans l’issue, notamment USBCore.cpp, USBDeviceClass et PluggableUSBModule. L’issue ne définit pas de modification concrète ; il faut donc d’abord établir le périmètre de compatibilité visé. Le travail sera terminé lorsqu’une API USB commune aux cores concernés aura été convenue.

Rédigé par le modèle d'indexation à partir du texte de l'issue.