[Logs onboarding] Expandable steps in onboarding flow

[yngrdyn]

As part of #159655 we introduced visual changes to the observability onboarding landing page as well as stream file flow (customLogs).

We have observe that in the Install elastic agent step the page grows vertically too much, as a fix for this we want to introduce expandable steps, so users can focus in the content of the current step and see the rest of the content as we progress in the flow.

This brings the following questions:

1. For the auto download is easy to know when step 2 (configure elastic agent) is complete but for users that doesn't want the auto configuration how do we know the step 2?
2. It looks kind of weird the empty steps, how do the user know they have to click in the step to expand it?

Additionally we have a technical constraint, since we are the ones managing the click events (to expand and collapse) we need to configure every intractable element within the step to stop the propagation to the parent so the step won't close unless it's intended to so.

Screen.Recording.2023-07-25.at.12.32.46.mov

I created an issue to EUI team to provide out of the box support for collapsible steps.

[yngrdyn]

One proposal from @isaclfreire is having a continue button so users can go to the next step

[elasticmachine]

Pinging @elastic/apm-ui (Team:APM)

[isaclfreire]

I am marking this one as blocked. Since the component behaviour is handled by the EUI team, it will be addressed and prioritized according to the team's roadmap. I'll share here any news / ETA for this task whenever there is updates.

Here's the discussion: elastic/eui#6987