Supporting readfrom_mem*(). writeto_mem() and a set of IRQs. Enabled by
default for SAMD51 devices and SAMD21 devices with external flash.
Tested with ItsyBitsy M4 and ItsyBitsy M0 with both on-board SoftI2C and a
RP2 Pico as controller.
Signed-off-by: Damien George <damien@micropython.org>
Signed-off-by: robert-hh <robert@hammelrath.com>
