Plan for edition 2024

[nicholasbishop]

Edition 2024 was stabilized in 1.85. There's no rush to switch to it, but we'll probably want to at some point (once 1.85 is old enough, per our MSRV policy).

Some of the necessary changes can be made prior to actually switching the edition:

• Switch rustfmt to the 2024 edition. This can be done separately from the edition in Cargo.toml by putting style_edition = "2024" in .rustfmt.toml. See also the style migration guide.
  • Since this will probably affect many lines of code, we might want to add this commit to .git-blame-ignore-revs.
• Enable the unsafe_op_in_unsafe_fn lint. This lint is enabled by default in 2024, and will affect many of our unsafe functions.
• Fix some "temporary value dropped while borrowed" errors. There are some changes to temporary lifetimes that affect code in device_path_gen.rs.

[phip1611]

The diff caused by the new rustfmt edition doesn't look too bad, IMHO