Add NETRC read support for rb_bundle_fetch to support authentication

[noahkawasakigoogle]

Add NETRC read support for rb_bundle_fetch to support authentication to private registries. Fixes #174

Taken from: bazelbuild/rules_rust#2623
Bazel 7.1.0 support for NETRC in utils: bazelbuild/bazel#20915

Example usage:

WORKSPACE

rb_bundle_fetch(
        name = "bundle",
        srcs = [
          ...
        ],
        gemfile = "//:Gemfile",
        gemfile_lock = "//:Gemfile.lock",
        env = {
            "NETRC": "~/.netrc"
        },
    )