Support providing datasets and copies in the upload flow

[hugomrdias]

In the demo app, user always has a dataset already create before uploading, with the multi sp upload flow it doesn't work anymore because i can't say use this dataset to put my files and i want 2 copies (product requirement).
Synapse SDK will return an error saying providerIds array length doesn't match the number of copies.

This goes back to my proposal here, the current upload options ( datasetIds: array, providerIds: array) makes this type of use case hard to do.

If the user wants to say put this files in these datasets (1, 2, 3, or more) and make sure i have datasets.length + 1 copies the current api does not support this.

/cc @rvagg

[rvagg]

But why are you pinning to a specific data set and not letting Synapse figure it out for you? Synapse will reuse existing and add more that you don't have and also handle the provider ping for you so you have a greater probability of actually getting stuff on chain?
I'm fine with exploring alternatives here, but I'd still argue that you're viewing this from an advanced user perspective with needs that are unlikely to be real user needs, for the SDK at least. And for advanced users that really have needs like this, then do provider selection yourself and store/pull/commit yourself so you own the full flow. I'm struggling to see a typical SDK user case where they show up with a single dataset or provider but want two copies.

[hugomrdias]

Depends on your definition of advanced user, for me non-advanced are developers building apps with synapse and advanced users are developers building services to add value and features on top of FOC.
I would argue even the non-advanced probably want to manage datasets, but not own the full upload pipeline that now is even more complex.

The current setup of manager and context does not provide a good api to manage datasets and pieces because its made to manage the upload pipeline. There's methods in the manager and others in the context. To use a context you need to create it manually.