[llvm] [libsycl] Implement fill & memset queue API (PR #217933)

[via llvm-commits]

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@@ -413,6 +413,87 @@ class _LIBSYCL_EXPORT queue {
   event memcpy(void *dest, const void *src, std::size_t numBytes,
                const std::vector<event> &depEvents);
 
+  /// Submits a memset operation for USM accessible on the device associated
+  /// with the queue. Equivalent to a fill operation with an unsigned char
+  /// pattern.
+  ///
+  /// \param ptr is the pointer to memory to be set.
+  /// \param value is the value the memory should be filled with, interpreted
+  /// as an unsigned char.
+  /// \param numBytes is the number of bytes to set.
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Robertkq wrote:

```suggestion
  /// \param numBytes is the number of bytes to set.
  /// \return an event that represents the status of the operation.
```
please add this to all of the exposed API

https://github.com/llvm/llvm-project/pull/217933