UI: Include global output parameters in Outputs tab

# Summary

I'm currently able to define a global output parameter in my spec, which I can either access using `argo get my-workflow`, programmatically, or looking at the yaml definition in the UI. I'd like to extent the `Output Artefacts` tab to also include any output parameters, for convenient visibility in the UI.

# Motivation

For explainability reasons, I would like to output a few global parameters once a workflow is completed. Ideally users of the platform in our company could more easily access this information by simply going to the `Outputs` (currently `Output Artefacts`) tab, instead of sifting through yaml to find them.

# Proposal

Split the `Output` tab into two sections: Artefacts and Global Parameters, and list out the parameters there.

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**Message from the maintainers**:

If you wish to see this enhancement implemented please add a 👍 reaction to this issue! We often sort issues this way to know what to prioritize.

Start at the UI's current Output Artefacts tab and trace how workflow global output parameters are exposed through the UI or YAML. The work is done when the Outputs tab is split into Artefacts and Global Parameters and the global parameters are listed for completed workflows.

Written by the indexing model from the issue text.