Consider wrapping beta extensions

As of https://github.com/JuliaGPU/OpenCL.jl/pull/311 , I can see that some extensions are missing. That doesn't make sense as wrap.jl does include `cl_ext.h` and the extensions are still present in https://github.com/JuliaGPU/OpenCL.jl/blob/master/res/wrap.jl

This shouldn't be a showstopper for the PR itself, but in the future I was planning to use the `cl_khr_command_buffer` extension to provide similar optimizations to OpenCL.jl as the ones provided by oneAPI's `command_list` API.

We need to look into why the script is not wrapping some extensions.