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[core]: Improve EventTarget listener exception safety  (#9872)

* [core]: Improve EventTarget listener exception safety

When an EventTarget listener throws an error, it should not prevent the
EventTarget from invoking other listeners registered for the same event
type.

In this commit we wrap event listener invocation with a `try/catch`, so
that each listener is more isolated from failures in others. This made
it difficult to observe issues in these listeners (which used to emit
synchronous errors), so we also add the `setEventListenerErrorHandler`
method which sets a callback that is invoked with the error and the
triggering event.

Breaking change
---------------

Previously, errors in event listeners would be synchronously thrown.
This behavior can be restored by re-throwing the exception inside the
error handler:

```ts
medplum.setEventListenerErrorHandler((error) => { throw error; })
```

This is _discouraged_, as it will cause listeners registered after the
throwing listener to not be invoked with the emitting event.

Signed-off-by: Noah Silas <noah@medplum.com>

* PR Feedback: include event type in default error message

Signed-off-by: Noah Silas <noah@medplum.com>

* PR Feedback: Remove error handling callback

Some thoughts informing this choice:
- The existing behavior (a synchronous throw on a listener error) was an
  implementation detail that deviates from common practices.

- We would like to keep these core APIs minimal. Adding new surface area
  for the error handling listener created an explicit contract that we
  would need to support.

- Callers adding a listener have the most context in what the
  appropriate error handling is. The best thing would be for each caller
  to wrap their callback in a `try`/`catch` and not emit errors that get
  caught by this framework code.

- That said, we still want to protect against situations where a
  callback _does_ throw; it should not prevent other listeners from
  receiving the same event, ... (continued)

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