Allow fab set to add non-existing annotations

[samiyaakhtar]

As an operator: I'd like to see additional metadata in the generated yaml about details such as author, time, release url, user who triggered the release etc. All this information is available as part of the release pipeline in Azure DevOps, it's a matter of leveraging it to include more information for auditing purposes.

Fabrikate could provide a command on a subcomponent/environment that lets you specify a collection of key/values to set at annotations. Fabrikate could determine if annotations already exist and handle appending additional key/values and avoiding duplicates. Currently, fab set is able to modify yaml to update image tags or similar, but it's missing the functionality to add an annotation if it doesn't exist.

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: my-app
  annotations:
    bedrock/releaseUrl: "https://dev.azure.com/abrig/efd47cfd-d35f-40ba-b424-e1ab432fdc68/_release?releaseId=37"
    bedrock/triggeredBy: "Andre Briggs"
    ...

Additional context: here