feat: expose @nodejs_host//:bin/node without using alias

[alexeagle]

This makes it possible for repository rules to reliably find a path to a node interpreter using rctx.path,
without having to hard-code any repository name.
Needed to workaround rctx.path not understanding alias, and repository rules not having any toolchain resolution.

[gregmagolan]

Should we a 2nd alias repository in this PR with our preferred name

    nodejs_repo_host_os_alias(
        name = name,
        user_node_repository_name = name,
    )

and then remove

    nodejs_repo_host_os_alias(
        name = name + "_host",
        user_node_repository_name = name,
    )

for 6.0?