Add request protocol.

[ioquatix]

Expose the request protocol to rack using a rack specific environment key.

This code can be improved but this is just a PoC. Later on, we can refactor this after considering how to handle Rack 2 / 3 differences.

Types of Changes

• New feature.

Testing

• [ ] I added tests for my changes.
• [ ] I tested my changes locally.
• [ ] I tested my changes in staging.
• [ ] I tested my changes in production.

[ioquatix]

Moved to protocol-rack gem.