RP2040 fixes (#2402)

Reduce default ESP32 factory partition size.
Doesn't need to be so big any more and allows more samples to build without customised hwconfig.
Size is now similar to other architectures.

Fix Rp2040 flash reading, destination buffer must be aligned.

Compiling IFS with -O3 throws error in Object::getRef. Avoid memcpy.

FlashString has missing #includes