Add a possibility to expand nested steps

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#### I'm submitting a ...
- [ ] bug report
- [x] feature request
- [ ] support request => Please do not submit support request here, see note at the top of this template.

#### What is the current behavior?
All nested steps have to be manually expanded.

#### What is the expected behavior?
Add simple link "expand".

#### What is the motivation / use case for changing the behavior?
Our reports have a lot of nested steps, we have to do very many clicks to see all steps.

Start by locating the report UI that renders nested steps and reviewing how their expanded state is controlled. Add a simple expand link for nested steps, then verify that it reveals all nested steps and avoids the current repeated manual clicks.

Written by the indexing model from the issue text.