Write a wrapper for the sha256

[ineskhou]

We're getting a pull request that introduces a file system validation tool that uses hashing to validate files
#270

RP2350 does have a hardware SHA accelerator, but it appears to not yet be implemented in CircuitPython. bring it online would help with upstream and potentially make the code run much faster!

https://github.com/raspberrypi/pico-sdk/blob/master/src/rp2_common/hardware_sha256/include/hardware/sha256.h

Acceptance Criteria

• sha256 runs with circuit python

Technical Details