[SYCL][Docs] Reintroduce device_ptr and host_ptr under namespace (#7814)

#7680 deprecated device_ptr and
host_ptr under the sycl namespace and intended to add them under the
sycl::ext::intel namespace instead, but did not. This commit adds them
to the namespace as originally intended. They are already implemented in
the extension headers.

Signed-off-by: Larsen, Steffen <[email protected]>

Author: steffenlarsen

sycl/doc/extensions/supported/sycl_ext_intel_usm_address_spaces.asciidoc

@@ -154,8 +154,9 @@ This constructor may only be called from within a command.
 
 === Explicit Pointer Aliases
 
-Add `device_ptr` and `host_ptr` aliases to the list of `multi_ptr` aliases as
-follows:
+Add `device_ptr`, `host_ptr`, `raw_device_ptr`, `raw_host_ptr`,
+`decorated_device_ptr`, and `decorated_host_ptr` aliases to the list of
+`multi_ptr` aliases as follows:
 ```c++
 namespace sycl {
 
@@ -176,6 +177,18 @@ using host_ptr =
 namespace ext {
 namespace intel {
 
+template<typename ElementType,
+         access::decorated IsDecorated = access::decorated::legacy>
+using device_ptr =
+    multi_ptr<ElementType, access::address_space::ext_intel_global_device_space,
+              IsDecorated>
+
+template<typename ElementType,
+         access::decorated IsDecorated = access::decorated::legacy>
+using host_ptr =
+    multi_ptr<ElementType, access::address_space::ext_intel_global_host_space,
+              IsDecorated>
+
 template<typename ElementType>
 using raw_device_ptr =
     multi_ptr<ElementType, access::address_space::ext_intel_global_device_space,