Update cargo to 2024 edition (#842)

Some effects of this change:
- New formatting changes across many files. No functionality changes
should occur from that.
- Calls to `set_env` are considered unsafe, since this only happens in
tests we wrap them in `unsafe` blocks

codex-rs/cli/src/main.rs

@@ -1,9 +1,9 @@
 use clap::Parser;
+use codex_cli::LandlockCommand;
+use codex_cli::SeatbeltCommand;
 use codex_cli::create_sandbox_policy;
 use codex_cli::proto;
 use codex_cli::seatbelt;
-use codex_cli::LandlockCommand;
-use codex_cli::SeatbeltCommand;
 use codex_exec::Cli as ExecCli;
 use codex_tui::Cli as TuiCli;