TreeView: `initialExpandedItems` should expand all parent items as well

[silvalaura]

Use Case The video goes kind of fast and then loops which makes it confusing, but the point is

• User selects a child item on the treeview
• This causes the page to navigate somewhere else or the user chooses to navigate somewhere else
• When the user gets back to the view with the treeview, they expect to still see the item they have clicked expanded

Acceptance Criteria

• If a nested item is passed to initialExpandedItems, all its parents are also expanded

Technical Notes

• Right now, our initialExpandedItems only expands the items passed to it and does not account for the parents of those items