Add functionality for group level alerting

[jelstongreen]

Is your feature request related to a problem? Please describe. It is tedious to have to list owners for each model individually when entire directories of models often belong to the same people.

Describe the solution you'd like With groups you can assign ownership like:

version: 2
groups:
  - name: my_group
    owner:
      name: My Team
      slack: my-team
      members: ['[email protected]','[email protected]]
      subscribers: ['[email protected]']

It would be amazing if we could parse the group level yml to determine who to tag in slack alerting which removes the requirement to add model level alert configuration.

Describe alternatives you've considered None

Additional context

Would you be willing to contribute this feature? Yes!