Set customizable alerts for Error Quota Notifications

### Problem Statement

We have had two incidents in the past when we unknowingly exceeded our error quota. By default, an email is sent to the account owner, but our account owner was on PTO at the time and our team did not realize we were not receiving alerts for a couple days. We need better alerting around error quota thresholds, specifically:

- the ability to send a Pager Duty alert when we reach 80%, 90% and 100% of our error quota

- the ability to send a message to a specific Slack channel when we reach 80%, 90% and 100% of our error quota

### Solution Brainstorm

_No response_

### Product Area

Settings - Spend Allocation