[Pitch] Add issue fields to JSON ABI schema

The event stream provides a stable interface for external tools to read test events. When encountering an issue while running tests, Swift Testing generates an event which includes a limited amount of issue metadata (severity and isKnown). We propose enriching this metadata with additional fields, so tools that consume it will be able to provide richer failure information to developers. Read the pitch here: SWT Pitch: add issue fields to JSON ABI schema by jerryjrchen · Pull Request #3396 · swi...