DISCO-3930 Make OHTTP work with old viaduct backend

[gruberb]

Navigate to the example directory

cd examples/viaduct-cli

Test OHTTP with the NEW backend (hyper-based, async)

cargo run --release --features ohttp -- --backend new ohttp

Test OHTTP with the OLD backend (reqwest-based, sync)

cargo run --release --features ohttp -- --backend old ohttp

Add -v for verbose trace logging

cargo run --release --features ohttp -- -v --backend old ohttp

Pull Request checklist

• Breaking changes: This PR follows our breaking change policy
  • This PR follows the breaking change policy:
    • This PR has no breaking API changes, or
    • There are corresponding PRs for our consumer applications that resolve the breaking changes and have been approved
• Quality: This PR builds and tests run cleanly
  • Note:
    • For changes that need extra cross-platform testing, consider adding [ci full] to the PR title.
    • If this pull request includes a breaking change, consider cutting a new release after merging.
• Tests: This PR includes thorough tests or an explanation of why it does not
• Changelog: This PR includes a changelog entry in CHANGELOG.md or an explanation of why it does not need one
  • Any breaking changes to Swift or Kotlin binding APIs are noted explicitly
• Dependencies: This PR follows our dependency management guidelines
  • Any new dependencies are accompanied by a summary of the due diligence applied in selecting them.

[bendk]

Looks good to me. I just had one, non-blocking, suggestion.

[bendk]

Could this be a method on Request? That would fit better with the current API IMO, but I don't want to bikeshed too much. However you want to expose the functionality is good with me.

[gruberb]

No, that's so much better! Thank you!

[gruberb]

Oh, I think we would have to make Request a uniffi::Object, which would be a breaking change?