VCIO-next: Improve advisories model and update pipelines

[tsteenbe]

After the initial creation of new advisory models, we faced multiple problems that imply we need to improve advisories model and update the corresponding pipelines

In particular this means:

• migrating to the Advisory V2 models in multiple small batches, and
• designing and implementing the many changes around the UI and API.

[pombredanne]

@TG1999 we are trying to see if subissues can be a thing to help!