Flash encryption support
Flash encryption support in build system, tooling
To come in future MR:
* On-device key generation on first boot (for production devices), need to finalise testing of bootloader entropy seeding.
* spi_flash_encrypted_write to support non-32-byte block writes (at least optionally.)
* I think a lot of the bootloader_support component can possibly be rolled into "spiflash" and other components, to use a common API.
See merge request !240
bab1d49f1f