Create proposal on how to abstract the workflow Runner definition

[mszostok]

Description

Currently, we are hard-coded to the Argo Workflows, which is our only built-in runner. As a result, we are also tight to Kubernetes. This is against our decision of making Capact generic. We should create abstracted workflow definition which can be implemented by others. Maybe we can do it base on already existing spec, e.g. https://serverlessworkflow.io/

Additionally, we need to figure out how to extract and share the common logic between different runners (e.g. Interface resolution).

Reason

Make Capact platform-agnostic - enable implementing Engine for other platforms.

Use cases

• User - enables them to use Capact with different engines, e.g. Kubernetes/bare-metal etc. and avoids platform-lock.
• Capact Developer - gives an option to create alternative engines, e.g. bare-metal. Now you need to bootstrap the whole k8s cluster to be able to just execute a single action.