• chore(SPI): align with ArduinoCoreAPI
• chore(SPI): remove non arduino transfer api with 2 buffer
• chore(SPI): clean up internal CS pin managements
• chore(SPI): remove deprecated WiFi library workaround

To be aligned with Arduino API:https://github.com/arduino/ArduinoCore-API/blob/master/api/HardwareSPI.h
Only Hardware CS pin support kept.
Allows to save memory space (arounf 1kB) and increase execution speed ( until 30%).

Fixes#257.
Supersede#2082.

Mainly follow recommendation from@matthijskooijman :#257 (comment)

Test old vs new

• Done on all series withGraphicTests
• Saved RAM space is 48 bytes for all series.
• Time measured betweenfillScreen and end ofsetup(). (note that it include delay's value i.e. 11000 ms).
• For STM32C0xx, all unnecessary features disabled to save space includingSerial. Adafruit libraries modified to remove dependencies within I2C. Time measured thanks a GPIO.

Test with Hardware CS managed by the library:

• Done withGraphicTests
• SetTFT_CS to-1 and addSPI.setSSEL(xx); before first call oftft.initR(INITR_BLACKTAB);