HAL folder organization (#14763)

Marlin/src/HAL/HAL.h

Marlin/src/HAL/HAL_AVR/fastio/fastio_1280.h

Marlin/src/HAL/HAL_AVR/fastio/fastio_1281.h

Marlin/src/HAL/HAL_AVR/fastio/fastio_168.h

Marlin/src/HAL/HAL_AVR/fastio/fastio_644.h

Marlin/src/HAL/HAL_AVR/fastio/fastio_AT90USB.h

Marlin/src/HAL/HAL_AVR/fastio_AVR.h

Marlin/src/HAL/HAL_AVR/inc/Conditionals_LCD.h

Marlin/src/HAL/HAL_AVR/inc/Conditionals_adv.h

Marlin/src/HAL/HAL_AVR/inc/Conditionals_post.h

Marlin/src/HAL/HAL_AVR/inc/SanityCheck.h

...in/src/HAL/HAL_DUE/dogm/u8g_com_HAL_DUE_shared_hw_spi.cpp

...in/src/HAL/HAL_DUE/dogm/u8g_com_HAL_DUE_st7920_sw_spi.cpp

Marlin/src/HAL/HAL_DUE/dogm/u8g_com_HAL_DUE_sw_spi.cpp

...in/src/HAL/HAL_DUE/dogm/u8g_com_HAL_DUE_sw_spi_shared.cpp

Marlin/src/HAL/HAL_DUE/dogm/u8g_com_HAL_DUE_sw_spi_shared.h

Marlin/src/HAL/HAL_DUE/fastio/G2_PWM.cpp

Marlin/src/HAL/HAL_DUE/fastio/G2_PWM.h

Marlin/src/HAL/HAL_DUE/fastio/G2_pins.h

Marlin/src/HAL/HAL_DUE/fastio_Due.h