Validate ntco::IoRing structures against kernel definitions, when possible

Support for `io_uring` was added in https://github.com/bloomberg/ntf-core/pull/24. For a variety of reasons, that implementation does not use the Linux kernel's definitions of `io_uring` structures, but re-declares them so that the `ntco_ioring` component is buildable on any Linux kernel version.

When possible, perform compile-time assertions that our reclaration of `io_uring` structures match the Linux kernels definitions.

Start with the ntco_ioring component and the re-declared io_uring structures introduced by pull request #24. Compare those declarations with the Linux kernel definitions where available, then add compile-time validation only when the definitions can be used. Done means mismatches are detected at compile time without preventing builds on unsupported kernel versions.

Written by the indexing model from the issue text.