feat: extension card

[MagicTINTIN]

Check availability for extension.

1. in
2. out
3. clock
4. GND
5. 3.3V

Protocol to be defined between them.

Extension with a pico ? or nano ? or else ?

• requirements for screen (Adresse I2C 0x3C)
• requirements for SD card R/W
• requirements for audio ? (jack)
• requirements for IR LED ?
• usb hub ?
• 5V ?