Fixes a visibility issue with rollup-worker

[Dig-Doug]

PR Checklist

Please check if your PR fulfills the following requirements:

• Tests for the changes have been added (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• [ x] Bugfix

What is the current behavior?

When using rules_nodejs from source, I get visibility errors:

WARNING: /home/doug/Development/rules_typescript_proto/test/BUILD.bazel:103:14: in rollup_bundle rule //test:test_es6_bundling: Target '//test:test_es6_bundling' violates visibility of target '@build_bazel_rules_nodejs//packages/rollup/bin:rollup-worker'. Continuing because --nocheck_visibility is active
WARNING: /home/doug/Development/rules_typescript_proto/test/BUILD.bazel:103:14: in @build_bazel_rules_nodejs//internal/providers:npm_package_info.bzl%node_modules_aspect aspect on rollup_bundle rule //test:test_es6_bundling: Target '//test:test_es6_bundling' violates visibility of target '@build_bazel_rules_nodejs//packages/rollup/bin:rollup-worker'. Continuing because --nocheck_visibility is active
WARNING: /home/doug/Development/rules_typescript_proto/test/BUILD.bazel:103:14: in @build_bazel_rules_nodejs//internal/common:module_mappings.bzl%module_mappings_runtime_aspect aspect on rollup_bundle rule //test:test_es6_bundling: Target '//test:test_es6_bundling' violates visibility of target '@build_bazel_rules_nodejs//packages/rollup/bin:rollup-worker'. Continuing because --nocheck_visibility is active
WARNING: /home/doug/Development/rules_typescript_proto/test/BUILD.bazel:103:14: in @build_bazel_rules_nodejs//internal/linker:link_node_modules.bzl%module_mappings_aspect aspect on rollup_bundle rule //test:test_es6_bundling: Target '//test:test_es6_bundling' violates visibility of target '@build_bazel_rules_nodejs//packages/rollup/bin:rollup-worker'. Continuing because --nocheck_visibility is active

What is the new behavior?

This PR makes this target public, which should fix it.

Does this PR introduce a breaking change?

• [x ] No

[alexeagle]

Thanks!