feat: add ability to output candidate releases

[niieani]

For the purposes of releasing, it is useful to just get the information of the packages that are about to be released.
If only: 'list-candidate-releases' is set, only output information about which packages would be released.

It provides releases_pending and paths_to_release as the outputs.

In order to enable this new feature, I've added a new input called only that allows running only the desired functionality ('create-github-releases' | 'list-candidate-releases' | 'update-pull-requests').
It is not a breaking change, and is backwards compatible with the skipGitHubRelease and skipGitHubPullRequest inputs.

[niieani]

Hi @chingor13! I know you must be busy. Any chance you could have a look at this? I'm open to feedback if you want any changes.
It would be really great if we could land a way to only output releases.

🙇

[le-yams]

Hi @niieani ,

I would be interested to also have a list-pull-requests feature for the only parameter.

Something like:

export async function main() {
  ...
  if (inputs.only === 'list-pull-requests') {
    core.debug('Listing pending pull requests');
    outputCandidatePRs(await manifest.buildPullRequests());
  }
  ...
}
...
function outputCandidatePRs(prs: ReleasePullRequest[]) {
  prs = prs.filter(pr => pr !== undefined);
  core.setOutput('prs_pending', prs.length > 0);
  if (prs.length) {
    core.setOutput('pr', prs[0]);
    core.setOutput('prs', JSON.stringify(prs));
  }
}

So in this case the pr and prs output would be of type ReleasePullRequest object instead of PullRequest object.

What do you think about it?
🙇

[niieani]

Hi @le-yams ! I think that's a good addition, however note that I've been trying to get this merged since October 2024.
I do hope @chingor13 can see this at some point in time, and review / give feedback / merge.
If you want to create a fork+commit your change, I can push it into this PR.