Remove Gimli and Xoodoo from the standard library

[jedisct1]

These are great permutations, and there's nothing wrong with them from a practical security perspective.

However, both were competing in the NIST lightweight crypto competition.

Gimli didn't pass the 3rd selection round, and is not much used in the wild besides Zig and libhydrogen. It will never be standardized and is unlikely to get more traction in the future.

Xoodyak, that Xoodoo is the permutation of, was a finalist.

It has a lot of advantages and might be standardized without NIST. But this is too early to tell, and too risky to commit to it in a standard library.

For lightweight crypto, Ascon is the one that we know NIST will standardize and that we can safely rely on from a usage perspective.

Gimli and Xoodoo served us well. Their code will be maintained, but outside the standard library.

It's sad to remove things from the standard library, but this is better done now rather than after Zig 1.0 is tagged.