Refactor error processing

This commit simplifies error serialization, relying on the advanced IPC for child processes & worker threads. Unnecessary code has been removed.

Possibly breaking changes:

* Renamed and removed fields from the undocumented AssertionError class, including the raw values
* Changes to the undocumented TAP output; stack traces are a bit worse, the rest is about the same but some fields have different names or values
* `nyc` stack frames are no longer ignored; we assume you're using the native code coverage tools

lib/api.js

@@ -305,13 +305,7 @@ export default class Api extends Emittery {
 			const files = scheduler.storeFailedTestFiles(runStatus, this.options.cacheEnabled === false ? null : this._createCacheDir());
 			runStatus.emitStateChange({type: 'touched-files', files});
 		} catch (error) {
-			if (error?.name === 'AggregateError') {
-				for (const error_ of error.errors) {
-					runStatus.emitStateChange({type: 'internal-error', err: serializeError('Internal error', false, error_)});
-				}
-			} else {
-				runStatus.emitStateChange({type: 'internal-error', err: serializeError('Internal error', false, error)});
-			}
+			runStatus.emitStateChange({type: 'internal-error', err: serializeError(error)});
 		}
 
 		timeoutTrigger.discard();