Allow for upload id to be retrieved or created by Storage api

[tomcham]

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Is your feature request related to a problem? Please describe.
What the problem is. Example: I'm always frustrated when [...]

Describe the solution you'd like
I'm using WriteChannel returned by https://googleapis.dev/java/google-cloud-storage/latest/com/google/cloud/storage/Storage.html#writer-com.google.cloud.storage.BlobInfo-com.google.cloud.storage.Storage.BlobWriteOption...- for streaming uploads. I have a use case where there is another process that might take over the resumable session, but in order to do that I need the upload id. Is it possible expose the upload id or allow creation of a resumable upload session?

Describe alternatives you've considered
Use WriteChannel#capture and serialize the object but is overly complex for my use case.

Additional context
Any other context or screenshots about the feature request.

[tomcham]

Hello, any plans to support this?

[tomcham]

@frankyn @BenWhitehead Any guidance on how to get the upload id after invoking Storage#writer? I couldn't find any public methods that expose this.