remove limitation on nested phases/steps

[sfc-gh-mchok]

Pre-review checklist

• [X] I've confirmed that instructions included in README.md are still correct after my changes in the codebase.
• [X] I've added or updated automated unit tests to verify correctness of my new code.
• [X] I've added or updated integration tests to verify correctness of my new code.
• [X] I've confirmed that my changes are working by executing CLI's commands manually on MacOS.
• [ ] I've confirmed that my changes are working by executing CLI's commands manually on Windows.
• [X] I've confirmed that my changes are up-to-date with the target branch.
• [ ] I've described my changes in the release notes.
• [X] I've described my changes in the section below.

Changes description

• Allow nesting phases/steps and also their usages in indents, since we found that we've had bugs multiple times from this and we don't want the console message mechanism to be breaking commands in prod

[sfc-gh-fcampbell]

I'm OK with this, might wanna run it y @sfc-gh-bdufour since he added the limitation initially