[SYCL] Accessor tags, CTAD and host_accessor

[iburyl]

This patch adds the implementation of SYCL_INTEL_accessor_simplification extension.

It adds:

• host_accessor
• read_only, write_only, read_write, read_constant tags
• noinit property
• a number of constructors for both buffer accessor and host_accessor to utilize newly added tags and properties for usage simplification

Most use cases for accessor has no longer need for specifying template arguments and rely on deduction guides and corresponding tags.

sycl::access::target is now accessible from sycl::target and sycl::access::mode from sycl::access_mode

[iburyl]

@mkinsner @jbrodman @rolandschulz
Initial PR on accessors simplification

[iburyl]

My local runs fail two abi tests:

  SYCL :: abi/layout_accessors.cpp
  SYCL :: abi/sycl_symbols_linux.dump

The reason: sycl::access::target was renamed into sycl::target, but using was added for keeping backward compatibility in this place:

namespace access {
using sycl::target;
}

What should I do: change the abi tests or make legacy declaration main one?

[romanovvlad]

My local runs fail two abi tests:

  SYCL :: abi/layout_accessors.cpp
  SYCL :: abi/sycl_symbols_linux.dump

The reason: sycl::access::target was renamed into sycl::target, but using was added for keeping backward compatibility in this place:

namespace access {
using sycl::target;
}

What should I do: change the abi tests or make legacy declaration main one?

I suggest making legacy declaration main one.

[jbrodman]

Do tests need to be rerun or are there outstanding issues?

[andreyfe1]

@iburyl, can we rely on merging this patch till the next Monday?

[jbrodman]

I would like to see this patch committed ASAP.