Allow the DefaultCondition on events to be string or object

[spolti]

fixes #157

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[spolti]

@ricardozanini it is ready to merge, the parse from the sdk go is working, however while generating the csv some objects goes with the different type, e.g.:

* spec.states[1].transition: Invalid value: "string": spec.states[1].transition in body must be of type object: "string"

By creating a customType e.g stringOrObject as we discussed earlier might not fix the issue since we would need to instruct the kubernetes controller-tools to inject our type and override that JSon schema, e.g. replace oneOf with anyOf, the same that is done with the intStr from apimachinery as seen here kubernetes-sigs/controller-tools@8fbbd2e

From the operator side we might have two options:

• Use the strict workflow object
• find a way to relax the objects (maybe using the model.Object typed as string) and unmarshall it to the desired object.

@davidesalerno please take a look here as well.

[spolti]

codecov again =/

[spolti]

There is e KEP opened for supporting the oneOf tag, but it seems not to be implemented yet.
This is a big discussion around this topic kubernetes-sigs/controller-tools#298

the KEP: https://github.com/kubernetes/enhancements/tree/master/keps/sig-api-machinery/1027-api-unions/README.md
There is another feature that might be helpful for us in the kubebuilder that will available on k8s 1.27 only: kubernetes/enhancements#2876