[llvm] [libsycl] add UT for kernel submission (PR #203931)

[Dmitry Rogozhkin via llvm-commits]

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@@ -430,6 +431,7 @@ class _LIBSYCL_EXPORT queue {
   std::shared_ptr<detail::QueueImpl> impl;
 
   friend sycl::detail::ImplUtils;
+  friend sycl::detail::MockQueue;
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dvrogozh wrote:

I afraid I still have the same concern as before. Basically by introducing `friend MyTestClass` with nowhere (for final user) declared `MyTestClass` in the public API we break encapsulation of the code. Exposing the whole class definition under `public` would have pretty similar effect I think.

https://github.com/llvm/llvm-project/pull/203931