[SPI] Moved SPI implementation directly into SPIBus

CMakeLists.txt

src/shared/drivers/spi/SPI.h

src/shared/drivers/spi/SPIBus.h

src/shared/drivers/spi/SPIBusInterface.h

src/shared/drivers/spi/SPIDefs.h

src/tests/drivers/dma/test-dma-spi-raw.cpp

src/tests/drivers/dma/test-dma-spi.cpp