Install CPU-optimized version of Stockfish

[fitztrev]

Closes #24

[dav1312]

Note that "modern" is technically deprecated
official-stockfish/Stockfish@d70a905

[fitztrev]

@dav1312 Thank you!

I noticed that the dev release of Stockfish is back to having other types (bmi2, vvni256, etc) in the Assets but the Stockfish 16 release just had avx2 and modern. Is that how it will be going forward? If so, I may just make those changes and have the app download the dev release.

[vondele]

In the future, yes, it will be renamed. However, I think the app should download a release and not a prerelease, just in case we introduce a bug in the development, the users of this app shouldn't notice that. Safer to stay with released binaries, IMO.

BTW, would it be meaningful for such an app to verify also the sha256sum of binaries it downloads, just to ensure the binary payload is the expected thing.