Rust in the 6.2 kernel

I can see many reasons why kernel-side programming is a different enough environment to need its own stdlib, and there is nothing fundamentally wrong with that. But on the other hand, I would expect some principles about how to grow this kernel-stdlib. (Some people have experience growing standard libraries for languages/environments and some idea are probably worth porting over from the start.)

For example (this is just a random idea, not a suggestion or anything) Rust-in-kernel could have decided to minimize the diff with outside-kernel Rust code by sticking to subsets of standard APIs or well-known third party packages whenever possible, or taking other steps to avoid divergence and reuse existing design choices. I see no trace of such a process in the [Either patchset](https://lwn.net/ml/linux-kernel/20221110164152.26136-28-o...), which does not make any mention of pre-existing Either code in Rust outside the kernel.