Allow nested sheets without boilerplate (#5660)

Co-authored-by: Hailey <me@haileyok.com>

modules/bottom-sheet/src/lib/Portal.tsx

@@ -0,0 +1,67 @@
+import React from 'react'
+
+type Component = React.ReactElement
+
+type ContextType = {
+  outlet: Component | null
+  append(id: string, component: Component): void
+  remove(id: string): void
+}
+
+type ComponentMap = {
+  [id: string]: Component
+}
+
+export function createPortalGroup_INTERNAL() {
+  const Context = React.createContext<ContextType>({
+    outlet: null,
+    append: () => {},
+    remove: () => {},
+  })
+
+  function Provider(props: React.PropsWithChildren<{}>) {
+    const map = React.useRef<ComponentMap>({})
+    const [outlet, setOutlet] = React.useState<ContextType['outlet']>(null)
+
+    const append = React.useCallback<ContextType['append']>((id, component) => {
+      if (map.current[id]) return
+      map.current[id] = <React.Fragment key={id}>{component}</React.Fragment>
+      setOutlet(<>{Object.values(map.current)}</>)
+    }, [])
+
+    const remove = React.useCallback<ContextType['remove']>(id => {
+      delete map.current[id]
+      setOutlet(<>{Object.values(map.current)}</>)
+    }, [])
+
+    const contextValue = React.useMemo(
+      () => ({
+        outlet,
+        append,
+        remove,
+      }),
+      [outlet, append, remove],
+    )
+
+    return (
+      <Context.Provider value={contextValue}>{props.children}</Context.Provider>
+    )
+  }
+
+  function Outlet() {
+    const ctx = React.useContext(Context)
+    return ctx.outlet
+  }
+
+  function Portal({children}: React.PropsWithChildren<{}>) {
+    const {append, remove} = React.useContext(Context)
+    const id = React.useId()
+    React.useEffect(() => {
+      append(id, children as Component)
+      return () => remove(id)
+    }, [id, children, append, remove])
+    return null
+  }
+
+  return {Provider, Outlet, Portal}
+}