[POR-340] Create an alerting notifications API

[mnafees]

Pull request type

Please check the type of change your PR introduces:

• [ ] Bugfix
• [ ] Feature
• [x] Other (please describe): Improvement

Pull request checklist

Please check if your PR fulfills the following requirements:

• [x] If it's a backend change, tests for the changes have been added and go test ./... runs successfully from the root folder.
• [ ] If it's a frontend change, Prettier has been run
• [ ] Docs have been reviewed and added / updated if needed

What is the current behavior?

Currently users need to add alerting rules manually to Prometheus.

What is the new behavior?

We now have a dedicated API that does the task for the users.

Technical Spec/Implementation Notes