work: account for task_group_base interface change in oneTBB 2022.0.0

The `m_wait_ctx` member being used in a narrow band of oneTBB versions was removed in a refactor that went into version [v2022.0.0](https://github.com/oneapi-src/oneTBB/releases/tag/v2022.0.0) which was released yesterday:
uxlfoundation/oneTBB@1f52f50

This change accounts for the update in the new version of oneTBB and uses the newly added `m_wait_vertex` member to access the same context as before.

Closes PixarAnimationStudios#3392

(Internal change: 2354795)

Author: mattyjams

pxr/base/work/dispatcher.cpp

@@ -34,7 +34,11 @@ WorkDispatcher::WorkDispatcher()
 #if TBB_INTERFACE_VERSION_MAJOR >= 12
 inline tbb::detail::d1::wait_context& 
 WorkDispatcher::_TaskGroup::_GetInternalWaitContext() {
+#if TBB_INTERFACE_VERSION_MINOR >= 14
+    return m_wait_vertex.get_context();
+#else
     return m_wait_ctx;
+#endif
 }
 #endif