Also disallows launching a SPIR-V kernel as a simple "range" kernel.
This seems consistent with our view that a "range" kernel is not just a
degenerate form of an nd-range kernel.  Since SPIR-V kernels always
have access to nd-range features, it does not make sense to launch them
as range kernels.  This is also consistent with our decision to limit
SYCL free function kernels to "nd-range" and "single-task" forms.

The OpenCL table describing legal kernel arguments had the opposite
order from the corresponding SPIR-V table.  The OpenCL table listed
the SYCL argument type in the left column while the SPIR-V table listed
the SYCL argument tupe in the right column.  I like the SPIR-V format
better, so change the OpenCL table to match.  This also adopts some of
the same wording from the SPIR-V table into the OpenCL one.

Clarify the iteration space and the user of work-item functions in the
OpenCL spec.  These changes closely follow the corresponding changes in
the SPIR-V spec.

Add a note referencing section C.7.7 of the core SYCL spec, which has
more details about the inverted sense of SYCL dimensions compared to
OpenCL.

Clarify that a single-task OpenCL and SPIR-V kernel can still use
features like `local_accessor` and group functions.  These are
well-defined because we already state that these single-task kernels
are launched as nd-range kernels with 1 work-item.

…ions

Use [source] block instead of triple backticks.