Rollup merge of #88230 - steffahn:a_an, r=oli-obk

Rollup merge of #88230 - steffahn:a_an, r=oli-obk

Fix typos “a”→“an”

Fix typos in comments; found using a regex to find some easy instance of incorrect usage of a vs. an.

While automation was used to find these, every change was checked manually.

Changes in submodules get separate PRs:
* https://github.com/rust-lang/stdarch/pull/1201
* https://github.com/rust-lang/cargo/pull/9821
* https://github.com/rust-lang/miri/pull/1874
* https://github.com/rust-lang/rls/pull/1746
* https://github.com/rust-analyzer/rust-analyzer/pull/9984
  _folks @ rust-analyzer are fast at merging…_
  * https://github.com/rust-analyzer/rust-analyzer/pull/9985
  * https://github.com/rust-analyzer/rust-analyzer/pull/9987
  * https://github.com/rust-analyzer/rust-analyzer/pull/9989

_For `clippy`, I don’t know if the changes should better better be moved to a PR to the original repo._

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This has some overlap with #88226, but neither is a strict superset of the other.

If you want multiple commits, I can split it up; in that case, make sure to suggest a criterion for splitting.