[Feature] Add the ability to set notifications from dbt-jobs-as-code

[b-per]

Describe the feature
In addition to defining jobs, some people might want to define mail/slack notifications for the jobs being defined. This could be added as an additional config on the jobs themselves.

Describe alternatives you've considered
Setting up notifications separately, either by hand in the UI or via the API called either manually or via Terraform.

Who will this benefit?
People wanting to manage jobs and notifications for those jobs at the same time.

Additional context
A few things to consider:

1. setting up notifications will require Account Admin access
2. we will need to interact with new endpoints
   • as the notifications "key" is the email/slack channel, this will require getting the current notifications for a given email and adding the new ones
3. what about notifications already set manually for those jobs?
4. what about removing all notifications for a job when those have been set previsouly outside of jobs-as-code or with jobs-as-code?