Add progress for OpenAI transcription request

[bilqisium]

This PR add progress report for OpenAI's transcription request, at least for the file uploading part.

I reused the AIProxyCertificatePinningDelegate to hook into the delegate method reporting progress.

Unfortunately, since Swift doesn't allow optional parameters in protocols, the progressCallback parameter is required at call site (but we can pass nil). This can be seen as a breaking change.

Also, it properly works only for OpenAIProxiedService, since the OpenAIDirectService architecture for having its URLSession doesn't allow injecting a delegate without significantly changing the internals.

This means that OpenAIDirectService never updates this callback, but it has to have it because of its conformance to
the OpenAIService protocol.

The transcription part wasn't unit tested, so I didn't add any tests either.

I tried to adhere to the style of the library.

If you have ideas on how to improve this PR or want some fixes, I'll happily implement them.

[lzell]

@bilqisium this is cool!

I think we can make this a nonbreaking change. You keep exactly what you have now, except you add a proto extension to OpenAIService.swift that looks like this:

extension OpenAIService {
    public func createTranscriptionRequest(
        body: OpenAICreateTranscriptionRequestBody
    ) async throws -> OpenAICreateTranscriptionResponseBody {
        return try await self.createTranscriptionRequest(body: body, progressCallback: nil)
   }
}

That should make existing callers happy.

Also, please add a check to the direct case that looks something like this:

    public func createTranscriptionRequest(snip) {
       if progressCallback != nil {
                 logIf(.error)?.error("progressCallback for transcription is not implemented")
       }
   }

[lzell]

Any advantage to keeping these accessors versus changing the ACL to public on:
public var progressCallback: ((Double) -> Void)?

[bilqisium]

No advantage indeed, it's much better to expose it indeed. 7982355

[bilqisium]

@bilqisium this is cool!

I think we can make this a nonbreaking change. You keep exactly what you have now, except you add a proto extension to OpenAIService.swift that looks like this:

extension OpenAIService {
    public func createTranscriptionRequest(
        body: OpenAICreateTranscriptionRequestBody
    ) async throws -> OpenAICreateTranscriptionResponseBody {
        return try await self.createTranscriptionRequest(body: body, progressCallback: nil)
   }
}

That should make existing callers happy.

Also, please add a check to the direct case that looks something like this:

    public func createTranscriptionRequest(snip) {
       if progressCallback != nil {
                 logIf(.error)?.error("progressCallback for transcription is not implemented")
       }
   }

Thank you @lzell, I've made the requested changes respectively in a030d78 and edb0f14.

[lzell]

Available in 0.106.0: https://github.com/lzell/AIProxySwift/releases/tag/0.106.0

Thank you @bilqisium !

[lzell]

Ah, we can now ditch these accessors and use (session.delegate as? AIProxyCertificatePinningDelegate)?.progressCallback = progressCallback since we exposed the member. I'll touch that up on main