[WIP]: S2 treeview haschildnodes

[snowystinger]

Closes

Attempt at fixing #7613 (comment)

✅ Pull Request Checklist:

• Included link to corresponding React Spectrum GitHub Issue.
• Added/updated unit tests and storybook for this change (for new code or code which already has tests).
• Filled out test instructions.
• Updated documentation (if it already exists for this component).
• Looked at the Accessibility Practices for this feature - Aria Practices

📝 Test Instructions:

🧢 Your Project:

[rspbot]

Build successful! 🎉

• View the storybook
• View the storybook-19
• View the storybook-17
• View the storybook-16
• View the S2 storybook
• View the documentation

[rspbot]

## API Changes

react-aria-components

/react-aria-components:UNSTABLE_TreeItem

 UNSTABLE_TreeItem <T extends {}> {
   aria-label?: string
   children: ReactNode
   className?: string | ((TreeItemRenderProps & {
     defaultClassName: string | undefined
 })) => string
   download?: boolean | string
+  hasChildItems?: boolean
   href?: Href
   hrefLang?: string
   id?: Key
   onHoverChange?: (boolean) => void
   onHoverStart?: (HoverEvent) => void
   ping?: string
   referrerPolicy?: HTMLAttributeReferrerPolicy
   rel?: string
   routerOptions?: RouterOptions
   style?: CSSProperties | ((TreeItemRenderProps & {
     defaultStyle: CSSProperties
 })) => CSSProperties | undefined
   target?: HTMLAttributeAnchorTarget
   textValue: string
   value?: {}
 }

/react-aria-components:TreeItemProps

 TreeItemProps <T = {}> {
   aria-label?: string
   children: ReactNode
   className?: string | ((TreeItemRenderProps & {
     defaultClassName: string | undefined
 })) => string
   download?: boolean | string
+  hasChildItems?: boolean
   href?: Href
   hrefLang?: string
   id?: Key
   onHoverChange?: (boolean) => void
   onHoverStart?: (HoverEvent) => void
   ping?: string
   referrerPolicy?: HTMLAttributeReferrerPolicy
   rel?: string
   routerOptions?: RouterOptions
   style?: CSSProperties | ((TreeItemRenderProps & {
     defaultStyle: CSSProperties
 })) => CSSProperties | undefined
   target?: HTMLAttributeAnchorTarget
   textValue: string
   value?: T
 }

---

@react-aria/gridlist

/@react-aria/gridlist:AriaGridListItemOptions

 AriaGridListItemOptions {
+  hasChildItems?: boolean
   isVirtualized?: boolean
   node: Node<unknown>
   shouldSelectOnPressUp?: boolean
 }

---

@react-aria/tree

/@react-aria/tree:AriaTreeGridListItemOptions

 AriaTreeGridListItemOptions {
+  hasChildItems?: boolean
   node: Node<unknown>
   shouldSelectOnPressUp?: boolean
 }

---

@react-spectrum/s2

/@react-spectrum/s2:TreeItemContent

+TreeItemContent {
+
+}

---

@react-spectrum/tree

/@react-spectrum/tree:TreeItemContent

+TreeItemContent {
+
+}

/@react-spectrum/tree:Collection

+Collection <T extends {}> {
+  addIdAndValue?: boolean
+  children?: ReactNode | ({}) => ReactNode
+  dependencies?: Array<any>
+  idScope?: Key
+  items?: Iterable<{}>
+}

---