[Bug]: Cannot define custom coreutils_toolchain

[snakethatlovesstaticlibs]

What happened?

coreutils_toolchain isn't publicly exported, however users may want to define a custom coreutils_toolchain because of some esoteric CPU architecture

For example, being able to define custom toolchains would help solve some of these problems:

• [Bug]: coreutils toolchain depends on glibc #701
• [Bug]: register_coreutils_toolchains's version attribute is fixed to a single value #671
• [Bug]: coreutils: Bad CPU type in executable (macOS Ventura arm64) #519

I'm currently using a patched version which exports the toolchain so we can use it in a definition. We should also consider doing this for other binaries as well (tar, etc.). If PRs are welcome, I can open a PR to implement this

Version

Development (host) and target OS/architectures: ARM / x86 centos 7

Output of bazel --version:

Bazelisk version: v1.17.0
Build label: 7.0.0
Build target: @@//src/main/java/com/google/devtools/build/lib/bazel:BazelServer
Build time: Mon Dec 11 16:50:16 2023 (1702313416)
Build timestamp: 1702313416
Build timestamp as int: 1702313416

Version of the Aspect rules, or other relevant rules from your
WORKSPACE or MODULE.bazel file:

faaada2eaa08de480f0db4fd1fcddead6aaed177 for bazel-lib

Language(s) and/or frameworks involved:
aspect_bazel_lib, aspect_rules_js

How to reproduce

No response

Any other information?

No response