EuiTreeView with node label or EuiListGroup as Tree

[clintandrewhall]

Problem

We've had multiple instances where we've needed an expanding tree whose items contain more than just a text label. Examples might include a tree with items with two or three button actions, a tooltip, code, etc.

EuiTreeView expands like a tree, but can only accept a string label.
EuiListGroup accepts complex items, but cannot expand like a tree.

Proposals

1. Refactor EuiTreeView to accept a React child. The label would then become the aria-label of the item.
2. Refactor EuiListGroupItem to accept both a React node label as well as a EuiListGroup child.
3. Create a new EuiListGroupItem, e.g. EuiListGroupTreeItem, which would accept some new configuration.

I'd prefer Option 2, as it seems the most pragmatic, but I'm open to other ideas and discussion. Thanks!

[cchaos]

#4352 Changed the label prop from string to ReactNode