Add support for specialization constants

[ndgrigorian]

This PR introduces support for specialization constants in dpctl, including both a Cython class SpecializationConstant for construction and passing of the constructed class to create_kernel_bundle_from_spirv via a new specializations keyword argument.

The SpecializationConstant class supports multiple constructors, including from Python buffers, a dtype string and a Python buffer (casting to the dtype via NumPy), and a number of bytes and a pointer as integers.

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[github-actions]

View rendered docs @ https://intelpython.github.io/dpctl/pulls/2304/index.html

[coveralls]

Coverage is 75.042% — feature/specialization-constants into rename-sycl-program-sycl-kernel-bundle. No base build found for rename-sycl-program-sycl-kernel-bundle.