Generalize `write_job_output` to an arbitrary object instead of "File"

[crich011]

In 2.0.0, we released write_job_output which adds a file to the job outputs. This mechanism can be extended without much effort to include all admissible platform object types.

[patr1ckm]

Yes, we should absolutely do this.

• I think Table would work transparently.
• It would be really nice ifJSONValue worked automatically too - the function serializes to JSON, then uploads.

I don't think it makes sense for this function to support Report, Project, or Credential.

[crich011]

Makes sense to me!