Limitation on creating multiple AugmentedVisualizations with the same visID and pluginResourceID

[amitgalitz]

Is your feature request related to a problem? Please describe.

Currently it is possible to create multiple Augmented Visualizations objects for the same visualization and the same plugin resource id. For example you can create with the same viz and same detector many visAugment objects. We will make sure this interaction isn't possible through the UI but there should still be some backstop from the API side.

Describe the solution you'd like

There should be a limitation that if a given visualization already has a visAugment object for the given pluginResourceId then you can't create another one.