19284: boards: support for the LILYGO TTGO T8 ESP32-S2 board r=benpicco a=gschorcht
### Contribution description
This PR provides the support for the LILYGO TTGO T8 ESP32-S2 board which has a OLED display (not yet supported) and a SD-Card slot on board.
The board is equipped with a USB-C connector that connects either to a USB-to-UART bridge or to the USB-OTG/JTAG interface of the ESP32-S2 via some DIP switches.
The PR includes a very small fix of printf format string in `tests/malloc`. I can split it off.
### Testing procedure
t.b.d.
### Issues/PRs references
19286: cpu/esp_common: use generic WIFI_SSID/WIFI_PASS defines r=benpicco a=benpicco
Co-authored-by: Gunar Schorcht <gunar@schorcht.net>
Co-authored-by: Benjamin Valentin <benpicco@beuth-hochschule.de>
b1be519107