Introduce command-buffer functionality to update cl_kernel in kernel command

[EwanC]

This is a feature request to enable updating the cl_kernel argument to clCommandNDRangeKernelKHR commands with clUpdateMutableCommandsKHR. This can be done by extending the cl_khr_command_buffer_mutable_dispatch extension, or creating a layered extension ontop of cl_khr_command_buffer_mutable_dispatch.

This request is based on a desire to use OpenCL as a backend to support an equivalent feature in SYCL-Graph (See intel/llvm#14896 & intel/llvm#15700). The other SYCL-Graph backends implement this feature using similar functionality to this feature request:

• CUDA-Graph - via cudaGraphExecKernelNodeSetParams, setting void * cudaKernelNodeParams::func.
• Level Zero - via zeCommandListUpdateMutableCommandKernelsExp. Note that when getting a handle to a kernel command in Level Zero, the list of possible kernels that are valid to update with must be passed (see zeCommandListGetNextCommandIdWithKernelsExp. If we want to follow a similar design, then an equivalent list can be passed via the properties parameter to clCommandNDRangeKernelKHR.