Provide enum type parameters for Argo workflows

[basanthjenuhb]

Summary

This is an enhancement to provide choice parameters as provided by Jenkins
Jenkins Example:

choice(name: 'CHOICE', choices: ['One', 'Two', 'Three'], description: 'Pick something')

A similar input parameter type could be provided for workflows. Something in the lines of

arguments:
    parameters:
    - name: choice
      defaultValue: one
      valueFrom:
           choices:
               - one
               - two
               - three

Use Cases

When would you use this?

Anyone who is submitting a workflow template from UI, would be able to specify arguments from the dropdown which has values from the choices array

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[alexec]

@jessesuen @basanthjenuhb want to work on this as part of hacktoberfest. I think we need to come up with a suitable way to specify the options, I'd lean more towards:

arguments:
    parameters:
    - name: choice
      defaultValue: one
      enum:
               - one
               - two
               - three

[basanthjenuhb]

Making the changes in #4314
UI PR coming up next

[basanthjenuhb]

Making the UI changes in #4365
@alexec can you help with the PR