v2.0.0 on Windows

I'm running into two problems trying to use rules_oci 2.0.0 on Windows.

1. It fails to download bsdtar, receiving a 404 code. This can be fixed by upgrading `aspect_bazel_lib`.
2. It fails to access zstd. It's pulling zstd out of `aspect_bazel_lib`, but that module doesn't support Windows for zstd.

A workaround for zstd would be appreciated if anyone has one. As things stand, I can't upgrade due to this problem on Windows, and I can't use the previous version due to a problem with MacOS (https://github.com/bazel-contrib/rules_oci/issues/509).

As an idea for a workaround, would it be possible for me to register a zstd toolchain in my own build files? I see that Meta provides an exe for Windows. It's in a zip file, but it seems like sufficient Bazel-fu should be able to turn that into a toolchain. It's beyond me, though.

For a real fix:

* Can zstd be optional? If you publish a 2.0.1 with optional zstd, that would allow me to upgrade on Windows.
* Perhaps use the official zstd module from Facebook? I don't know the trade offs, but it seems odd for rules_oci to pull in zstd from aspect_bazel_lib.

Start by reproducing the bsdtar 404 and zstd access failures on Windows with rules_oci 2.0.0, then trace the dependencies through aspect_bazel_lib. Compare the proposed optional-zstd and registered Windows zstd toolchain approaches; done means rules_oci can be upgraded and used successfully on Windows.

Written by the indexing model from the issue text.