[wit-bindgen-rust] Fix 2024 edition compat (#1205)

* [wit-bindgen-rust] cargo fix --edition

* fix "unsafe op in unsafe fn" 2024 change

* fix cargo fmt output

* rust-xcrate-test: make edition="2024" to show bindings work in 2024

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Co-authored-by: Yosh <github@yosh.is>

Author: pchickey