I²C for u8g2 with ssd1306

[pcbreflux]

Adding i²C to the u8g2_esp32_hal and include a sample task

• still don't know why the i²C have to be set (0x3C)
• still don't know why the I²C commandcode have to be added (0x00 or 0x40)

[nkolban]

There are reports coming in that this commit broke the SPI usage ...

From the IRC #ESP32 chatroom ...

<bleader> kolban: apparently pcbreflux commit in u8g2_esp32_hal breaks spi
<bleader> there is a chunk of code removed, that leaves the spi handle unitiliazed
<bleader> went back to a version before his commit and managed to get the hello world working
<bleader> (crazy how having a screen displaying text can make a man happy...)