chore: Prepare for Rust edition bump to 2024 (without autofix) (#27791)

Successor to #27779 - in this PR I've applied changes manually, without
futzing with if let lifetimes at all.

Release Notes:

- N/A

crates/fsevent/src/fsevent.rs

@@ -365,7 +365,7 @@ impl std::fmt::Display for StreamFlags {
 }
 
 #[link(name = "CoreServices", kind = "framework")]
-extern "C" {
+unsafe extern "C" {
     pub fn FSEventsGetCurrentEventId() -> u64;
 }