CI: Provide SHA256 checksums for all build artifacts in the CI artifacts list

[rt121212121]

This should provide a way to know if an artifact that one has locally, is the one that was built on CI.

[AustEcon]

So to do this would I get the pipeline to hash the final python .whl... and have azure pipelines save the hashes as an artifact alongside the python wheels?? (build-hashes.txt)

Then when cutting a new release would manually update a build-hashes.txt file at the top-level of this repository for people to verify against? (similar to this: https://github.com/electrumsv/electrumsv/blob/master/build-hashes.txt)

[rt121212121]

Sure.