Support Unix socket allowlists in macOS sandbox (#17654)

## Changes

Allows sandboxes to restrict overall network access while granting
access to specific unix sockets on mac.

## Details

- `codex sandbox macos`: adds a repeatable `--allow-unix-socket` option.
- `codex-sandboxing`: threads explicit Unix socket roots into the macOS
Seatbelt profile generation.
- Preserves restricted network behavior when only Unix socket IPC is
requested, and preserves full network behavior when full network is
already enabled.

## Verification

- `cargo test -p codex-cli -p codex-sandboxing`
- `cargo build -p codex-cli --bin codex`
- verified that `codex sandbox macos --allow-unix-socket /tmp/test.sock
-- test-client` grants access as expected

codex-rs/cli/Cargo.toml

@@ -45,6 +45,7 @@ codex-state = { workspace = true }
 codex-stdio-to-uds = { workspace = true }
 codex-terminal-detection = { workspace = true }
 codex-tui = { workspace = true }
+codex-utils-absolute-path = { workspace = true }
 codex-utils-path = { workspace = true }
 libc = { workspace = true }
 owo-colors = { workspace = true }