[llvm] [libsycl] implement methods of synchronization in event and queue classes (PR #205860)

[Sergey Semenov via llvm-commits]

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@@ -166,14 +166,26 @@ class _LIBSYCL_EXPORT queue {
   /// exceptions.
   void wait();
 
+  /// Blocks the calling thread until all commands previously submitted to this
+  /// queue have completed. Synchronous errors are reported through SYCL
+  /// exceptions. At least all unconsumed asynchronous errors held by this queue
+  /// are passed to the appropriate async_handler.
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sergey-semenov wrote:

There's a discrepancy with the `throw_asynchronous` comment then. Personally, I think referring to the default async handler as the one associated with the queue is fine.

https://github.com/llvm/llvm-project/pull/205860