FEATURE REQUEST: Group alerts by custom filter

Sometimes the fingerprinting of errors isn’t enough-- e.g. the Sentry UI will group all errors of a certain type together, even if they originate in different places or with different contexts within the application. I know there are error boundary tools for React component trees, but it would be very useful to be able to split errors in the UI based on filter criteria after the fact.

It would be useful to be able to split out or group subsets of errors from the UI. You can filter down on a certain url or other tag, but it would be great to be able to then split off those selected/filtered errors into their own group and have future errors that match be grouped accordingly.