Registering all toolchains does not work

[NEOatNHNG]

Registering all toolchains via @score_toolchains_rust//toolchains/ferrocene:all as described in the README doesn't work because of bazelbuild/bazel#16298 which prevents :all from matching aliases.

However if we do it like this then bazel will download the dependency no matter whether it matches the platform we want to target:

register_toolchains(
    "@score_toolchains_rust//toolchains/ferrocene:ferrocene_x86_64_unknown_linux_gnu",
    "@score_toolchains_rust//toolchains/ferrocene:ferrocene_aarch64_unknown_linux_gnu",
    "@score_toolchains_rust//toolchains/ferrocene:ferrocene_x86_64_pc_nto_qnx800",
    "@score_toolchains_rust//toolchains/ferrocene:ferrocene_aarch64_unknown_nto_qnx800",
    dev_dependency = True,
)

A solution might be to do the toolchain registration in a macro which can then be used by the using module.

[NEOatNHNG]

Note: right now the "solution" is to register the toolchains via bazelrc