cl_intel_unified_shared_memory version 1.1

[bashbaug]

Updates the cl_intel_unified_shared_memory extension to version 1.1:

• Version 1.1 relaxes error conditions for clSetKernelArgMemPointerINTEL and clSetKernelExecInfo(CL_KERNEL_EXEC_INFO_USM_PTRS_INTEL) to allow passing any arbitrary pointer to a kernel even without system USM. It is only a programming error (specifically, undefined behavior) to dereference an arbitrary pointer in a kernel.
• Also adds a few issues for questions that have been raised in the last couple of months.

I'll probably keep this a draft PR for a bit, to provide opportunity for additional commentary and while we implement this behavior.

CC: @gmlueck