[FEATURE]: Provide separate action output for stdout and stderr

[WillDaSilva]

Feature Request

Background / Motivation

Currently I use exec actions to fetch various credentials, which are then used by downstream actions/deployments by accessing the credentials with ${actions.run.<name>.outputs.log}.

What should the user be able to do?

In addition to ${actions.run.<name>.outputs.log}, which provides stdout and stderr combined, we should be able to access ${actions.run.<name>.outputs.stdout} and ${actions.run.<name>.outputs.stderr}.

Why do they want to do this? What problem does it solve?

The tools I'm running in my exec actions will log the part that I want to use (e.g. an access token) to stdout, while they'll log other useful information for the user to stderr. I only want to use the part that's sent to stdout, but since Garden only provides the two streams combined, I have to redirect stderr to /dev/null. Ideally, we'd let stderr get printed since it has useful information, without necessarily combining the streams in the action output.

How important is this feature for you/your team?

🌹 It’s a nice to have, but nice things are nice 🙂