Add GraphNode example for Cxx TMs (#41766)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/41766

Changelog: [Internal]

Adds a simple example showing a recursive node, stored inside a collection in a Cxx TM.

Currently we can't auto-generate [the necessary C++ Types](https://reactnative.dev/docs/next/the-new-architecture/cxx-custom-types#struct-generator) - but we can add it later if this scenarios becomes really common.

Reviewed By: rshest

Differential Revision: D51783974

fbshipit-source-id: 7352db1a354cd7da32febc650f7cc5e10dd16d2d

packages/rn-tester/js/examples/TurboModule/NativeCxxModuleExampleExample.js

@@ -42,6 +42,8 @@ type Examples =
   | 'getBool'
   | 'getConstants'
   | 'getCustomEnum'
+  | 'getCustomHostObject'
+  | 'getGraphNode'
   | 'getNumEnum'
   | 'getStrEnum'
   | 'getMap'
@@ -102,6 +104,11 @@ class NativeCxxModuleExampleExample extends React.Component<{||}, State> {
       NativeCxxModuleExample?.consumeCustomHostObject(
         NativeCxxModuleExample?.getCustomHostObject(),
       ),
+    getGraphNode: () =>
+      NativeCxxModuleExample?.getGraphNode({
+        label: 'root',
+        neighbors: [{label: 'left'}, {label: 'right'}],
+      }),
     getNumEnum: () => NativeCxxModuleExample?.getNumEnum(EnumInt.IB),
     getStrEnum: () => NativeCxxModuleExample?.getStrEnum(EnumNone.NB),
     getNumber: () => NativeCxxModuleExample?.getNumber(99.95),