@uppy/companion: deprecate RequestClient options

[aduh95]

Deprecate RequestClient options in favor of less Companion-centered ones so this class can be reused in non-Companion setup.

[Murderlon]

I don't think we should make this change.

• This seems to be an XY problem.
• companion-client is specifically made as an interface for Companion. Therefor it's good to have that tightly coupled.
• 99% of the use cases, which is remote file downloads, can only be done with a companion instance (standalone or integrated) and not a random backend endpoint.
• I'm assuming the use case here is catering for S3 signing requests to your own backend which coincidentally would have the exact same structure as Companion, saving boiler plate
  • we now strongly discourage using Companion for signing, so this change seems to be exclusively for something we don't want to encourage.
  • this change would implicitly mean that changes between the Companion client and server now also impact customers, instead of just a surface area we control.
  • to me it seems more likely people would want to define their own endpoints. Making this future breaking change for an edge case usage even more edge case.
• All the docs and examples would need to be updated (eventually) and another breaking change people would need to migrate from.

[aduh95]

I think we should do it, not doing it forces devs to serve a ton of useless bytes re-implementing what's already in @uppy/companion-client to handle these requests.

to me it seems more likely people would want to define their own endpoints

It's part of the plan, see 686f2d0.

[Murderlon]

I think we should do it, not doing it forces devs to serve a ton of useless bytes re-implementing what's already in @uppy/companion-client to handle these requests.

Did you read my points? This is a proposal for a breaking change for something that Companion should not be used for. After strong discouragement from us in the docs, if someone still likes use Companion for this, and then in the unlikely event of wanting to exactly mimic companion of this already unlikely event, I think they can just do the boiler plate. And if that's a problem, then this perhaps a XY problem after all, because we could come up with alternatives to ease that pain.