[compute_unit_v2] Initial definition for new compute unit pins (untested)

...stm32f7/stm32f767zi_compute_unit_v2/core/stage_1_boot.cpp

...7zi_compute_unit_v2/interfaces-impl/arch_registers_impl.h

...m32f7/stm32f767zi_compute_unit_v2/interfaces-impl/bsp.cpp

...f7/stm32f767zi_compute_unit_v2/interfaces-impl/bsp_impl.h

..._stm32f7/stm32f767zi_compute_unit_v2/stm32_2m+16m_xram.ld

..._stm32f7/stm32f767zi_compute_unit_v2/stm32_2m+384k_ram.ld

...exM7_stm32f7/stm32f767zi_compute_unit_v2/board_settings.h

miosix/config/boards.cmake

miosix/config/options.cmake