Provide clarity on future of tokenless uploads from GitHub Actions

[lpsinger]

v4 dropped support for tokenless uploads on GitHub Actions due to #1068 ("use cli instead of node uploader"). In the PR description there is the comment:

Notes to reviewer:

• Currently tokenless upload is not supported. Releasing this PR for users who are not using a codecov token will break their CI

Is there a plan to restore support for tokenless uploads in the the GitHub Action going forward? Tokenless uploads still work with v3, the Node uploader obviously still supports tokenless uploads. Will the CLI uploader gain support for them? The Codecov documentation still mentions tokenless uploads in lots of places.

[louwers]

Despite mentioning "PRs made from forks to the upstream public repos will support tokenless" in the changelog, this does not seem to be working at all.