Plugin functionality to allow users to extend kubernetes/Argo workflows functionality supported by Metaflow.

[roofurmston]

Metaflow allows certain pieces of kubernetes/argo workflows to be specified in flows via the kubernetes and schedule decorators and the kubernetes or argo-workflows flags. However, Argo workflows is a very complex tool with a wide range of different options for configuring workflows.

Rather than expecting Metaflow to cover the whole range of functionality provided by Argo workflows, the suggestion of this issue is that it provides plugin type functionality. This would enable end users to extend the kubernetes. This would prevent Metaflow from becoming a blocker on end users using pieces of kubernetes/Argo workflows functionality that suits their needs.