dev-proxy: Reimplement em_proxy

[SternXD]

Reimplements (em_proxy) tool using the new idevice libraries. This tool gives a proxy for TCP packets to work around iOS loopback limitations by modifying packets and retransmitting them through a tunnel.

Changes

• Reimpled em_proxy binary with support for both WireGuard and CoreDeviceProxy tunnel modes
• Added CoreDeviceProxy support with proper address translation (localhost <-> tunnel IPs)
• Updated core_device_proxy_tun.rs to use the new tun-rs 2.7.4 API (DeviceBuilder instead of the deprecated one)
• Implemented address translation for CoreDeviceProxy mode:
  • Outbound: Translates 127.0.0.1 to tunnel IPs (client/server from CoreDeviceProxy handshake)
  • Inbound: Translates tunnel IPs back to 127.0.0.1
• WireGuard mode uses IP address swapping (bytes 12-15 <-> 16-19) as in the original implementation
• Added key loading for WireGuard keys from CLI args, files, or default directories

Tech Details

• Uses tun-rs for TUN in CoreDeviceProxy mode
• Uses boringtun for WireGuard handling
• feature-gates WireGuard specific code with #[cfg(feature = "wireguard")]
• CoreDeviceProxy mode is the default/recommended approach (in my opinion)

Testing

• Compiles with both wireguard and core-device features
• Passes just macos-ci-check
• Passes cargo fmt --check
• Needs testing (other then just compiling it)

Related

Based on the original implementation (https://github.com/jkcoxson/em_proxy)