refactor: ping tutorial using tokio

[P1R]

Description

By identifying the missing examples and tests for solving #4449 I identified that the ping tutorial still uses async-std and there is an already refactored tokio ping example. Upon opening, there are some slight differences that might require review.

Motivation

The tokio runtime is much more well established and better maintained. Users should be able to use other runtimes or bring their own.[#4449]

Examples and tests where considered in #4449 but not this tutorial.

Current Implementation

Both runtimes are being mixed.[#4449]

• async-std in ping tutorial
• tokio in ping example

Are you planning to do it yourself in a pull request ?

Yes

[P1R]

Differences between the ping example and the ping tutorial

Cargo.toml

• libp2p missing features from tutorial in the example: “tls”, “dns” “websocket”, and “macros”
• using latest version of the dependencies: SHOULD we use specific versions?

src/main.rs

• SwarmBuilder tcp config does not implement tcp but noise instead
• Ping timeout in the tutorial is 30 seconds while in the example is Duration::from_secs(u64::MAX)

Self-reviewed code before modifying the rust-doc tutorial:

• https://github.com/P1R/rust-libp2p-tutorial

[P1R]

Solved on PR: #5559