Add overloads for snapshot functions to expose download speed

[adrgrondin]

Summary

This PR introduces new overloads for the snapshot functions’ progress handlers that expose download speed (in bytes/s).

The new overloads are fully backward compatible, existing APIs remain unchanged.

Changes

• Example overload:

  @discardableResult 
  func snapshot(
      from repo: Repo, 
      revision: String = "main", 
      matching globs: [String] = [], 
      progressHandler: @escaping (Progress, Double?) -> Void
  ) async throws -> URL {
      try await snapshot(from: repo, revision: revision, matching: globs) { progress in
          let speed = progress.userInfo[.throughputKey] as? Double
          progressHandler(progress, speed)
      }
  }

Download speed printed in code compared against Xcode’s Network Report:

[FL33TW00D]

@adrgrondin Great contribution thank you!

Could we add a test that accumulates some recorded speed in an array or something for a given download? Just to be sure it doesn't get broken in the future :)

Also swiftformat'ing

[adrgrondin]

Thanks @FL33TW00D

I added a .snapshot() test case with speed, similar to other tests in the repo (real download).

I can run swift-format but this led to 33 files changed, so not sure if I'm doing something wrong with the command or if the project has not been formatted in a while. If it is the latter I would suggest to separate the formatting in a PR and I will rebase.

[FL33TW00D]

LGTM cc: @pcuenca

[pcuenca]

Looks great! Appreciate the carefulness in keeping it non-breaking 🙌

We use a pinned version of the formatter because we've seen great rule divergence (as you experienced too). I took the liberty to run it locally and commit to your PR.

[pcuenca]

nice!

[pcuenca]

Ah, this is just a shortcut for the value in .throughputKey 👍

[pcuenca]

honestly, I hate that the formatter gets involved with this at all 😭 The previous version was clearer in my opinion cc @FL33TW00D @adrgrondin

[pcuenca]

Apologies for the failed CI run, we are in the process of fixing it. Tests pass locally, so merging!