* Initial command-buffer tests
Introduce some basic testing of the
[cl_khr_command_buffer](https://www.khronos.org/registry/OpenCL/specs/3.0-unified/html/OpenCL_Ext.html#cl_khr_command_buffer)
extension. This is intended as a starting point from which we can iteratively build up tests
for the extension collaboratively.
* Move tests into derived classes
* Move tests from methods into derived classes implementing
a `Run()` interface.
* Fix memory leak when command_buffer isn't freed when a test
is skipped.
* Print correct error code for
`CL_DEVICE_COMMAND_BUFFER_CAPABILITIES_KHR`
* Pass `nullptr` for queue parameter to command recording entry-points
* Define command-buffer type wrapper
Other OpenCL object have a wrapper to reference count their use
and free the wrapped object. The command-buffer object can't use
the generic type wrappers which are templated on the appropriate
release/retain function, as the release/retain functions are
queried at runtime.
Instead, define our own command-buffer wrapper class where a base
object is passed on construction which contains function pointers
to the release/retain functions that can be used in the wrapper.
* Use create_single_kernel_helper_create_program
Use `create_single_kernel_helper_create_program` rather than
hardcoding `clCreateProgramWithSource` to allow for other types
of program input.
Also fix bug using wrong enum for passing properties on command-buffer
creation, should be `CL_COMMAND_BUFFER_FLAGS_KHR`
* Add out-of-order command-buffer test
Introduce a basic test for checking sync-point use
with out-of-order command-buffers.
This also includes better checking of required queue properties.
