Introduce `rewind` and `rewindable?` as a general concept.

[ioquatix]

There are situations where we need to rewind the input or output, for example idempotent request handling and redirects. Previously, body.respond_to?(:rewind) was used but it's better to expose a predicate.

In addition, I noticed that we have two usage of wrap(body) and wrap(request|response). I'd like to use a different method name if possible, and this also applies to rewindable body wrappers.

Types of Changes

• New feature.
• Maintenance.

Contribution

• [x] I added tests for my changes.
• [x] I tested my changes locally.
• [x] I agree to the Developer's Certificate of Origin 1.1.