Auto merge of #83377 - Mark-Simulacrum:stable-next, r=Mark-Simulacrum

[stable] 1.51.0 release

Also includes backports of the release notes, as well as:

*  SplitInclusive is public API #83372
*  std: Fix a bug on the wasm32-wasi target opening files #82804
*  Fix io::copy specialization using copy_file_range when writer was opened with O_APPEND #82417

r? `@Mark-Simulacrum`
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