[NFC][SYCL] Break include's cycle (#1770)

This changes is required for #1747.

Suppose we add `#include <CL/sycl/accessor.hpp>` in `interop_handle.hpp` . Furthermore we will add `#include <CL/sycl/interop_handle.hpp>` to `include/CL/sycl/handler.hpp`. Then, we will have the following cycle (here `->` says `which includes`):

```
handler.hpp -> interop_handle.hpp -> accessor.hpp -> handler.hpp (cycle here)
```

Also, this patch eliminates use of `reinterpret_cast` (either as it is or C-style) when converting `accessor` to `AccessorBaseHost` at host.

Author: s-kanaev

sycl/include/CL/sycl/accessor.hpp

@@ -15,10 +15,10 @@
 #include <CL/sycl/detail/common.hpp>
 #include <CL/sycl/detail/export.hpp>
 #include <CL/sycl/detail/generic_type_traits.hpp>
+#include <CL/sycl/detail/handler_proxy.hpp>
 #include <CL/sycl/detail/image_accessor_util.hpp>
 #include <CL/sycl/detail/image_ocl_types.hpp>
 #include <CL/sycl/exception.hpp>
-#include <CL/sycl/handler.hpp>
 #include <CL/sycl/id.hpp>
 #include <CL/sycl/image.hpp>
 #include <CL/sycl/pointers.hpp>
@@ -846,7 +846,7 @@ class accessor :
             detail::convertToArrayOfN<3, 1>(BufferRef.get_range()), AccessMode,
             detail::getSyclObjImpl(BufferRef).get(), Dimensions, sizeof(DataT),
             BufferRef.OffsetInBytes, BufferRef.IsSubBuffer) {
-    CommandGroupHandler.associateWithHandler(*this);
+    detail::associateWithHandler(CommandGroupHandler, this, AccessTarget);
   }
 #endif
 
@@ -888,7 +888,7 @@ class accessor :
             detail::convertToArrayOfN<3, 1>(BufferRef.get_range()), AccessMode,
             detail::getSyclObjImpl(BufferRef).get(), Dimensions, sizeof(DataT),
             BufferRef.OffsetInBytes, BufferRef.IsSubBuffer) {
-    CommandGroupHandler.associateWithHandler(*this);
+    detail::associateWithHandler(CommandGroupHandler, this, AccessTarget);
   }
 #endif
 
@@ -932,7 +932,7 @@ class accessor :
                          AccessMode, detail::getSyclObjImpl(BufferRef).get(),
                          Dimensions, sizeof(DataT), BufferRef.OffsetInBytes,
                          BufferRef.IsSubBuffer) {
-    CommandGroupHandler.associateWithHandler(*this);
+    detail::associateWithHandler(CommandGroupHandler, this, AccessTarget);
   }
 #endif
 
@@ -1238,7 +1238,10 @@ class accessor<DataT, Dimensions, AccessMode, access::target::image,
                                access::target::image, IsPlaceholder>(
             Image, CommandGroupHandler,
             (detail::getSyclObjImpl(Image))->getElementSize()) {
-    CommandGroupHandler.associateWithHandler(*this);
+#ifndef __SYCL_DEVICE_ONLY__
+    detail::associateWithHandler(CommandGroupHandler, this,
+                                 access::target::image);
+#endif
   }
 #ifdef __SYCL_DEVICE_ONLY__
 private:
@@ -1313,7 +1316,10 @@ class accessor<DataT, Dimensions, AccessMode, access::target::image_array,
                                access::target::image, IsPlaceholder>(
             Image, CommandGroupHandler,
             (detail::getSyclObjImpl(Image))->getElementSize()) {
-    CommandGroupHandler.associateWithHandler(*this);
+#ifndef __SYCL_DEVICE_ONLY__
+    detail::associateWithHandler(CommandGroupHandler, this,
+                                 access::target::image_array);
+#endif
   }
 
   detail::__image_array_slice__<DataT, Dimensions, AccessMode, IsPlaceholder>

sycl/include/CL/sycl/detail/buffer_impl.hpp

@@ -14,7 +14,6 @@
 #include <CL/sycl/detail/export.hpp>
 #include <CL/sycl/detail/helpers.hpp>
 #include <CL/sycl/detail/sycl_mem_obj_t.hpp>
-#include <CL/sycl/handler.hpp>
 #include <CL/sycl/property_list.hpp>
 #include <CL/sycl/stl.hpp>
 #include <CL/sycl/types.hpp>
@@ -32,7 +31,6 @@ template <typename DataT, int Dimensions, access::mode AccessMode,
 class accessor;
 template <typename T, int Dimensions, typename AllocatorT, typename Enable>
 class buffer;
-class handler;
 
 using buffer_allocator = detail::sycl_memory_object_allocator;