Add interop tests between py-libp2p and rust-libp2p for ping protocol

[paschal533]

Description

This PR adds interoperability tests between py-libp2p and rust-libp2p implementations, focusing on the ping protocol over TCP transport.

What does this PR do?

• Creates a new interop/rust directory structure for testing py-libp2p against rust-libp2p implementations
• Implements a comprehensive test for the ping protocol that can:
  • Test py-libp2p client → rust-libp2p server
  • Test rust-libp2p client → py-libp2p server
  • Test bidirectional communication
• Provides documentation and scripts to easily run the tests

How to test

1. Make sure you have both py-libp2p and rust-libp2p repositories cloned
2. Follow the instructions in the tests/interop/rust/README.md file
3. Run ./tests/interop/rust/run_tests.sh