Use a logger name less likely to conflict.
Log writer looks for an exception object in event.extra.
Errors log getMessage and the original Exception.

This means the NewRelic error type will be Exception instead of NoticedError and
the message will prettier since it doesn't contain a redundant stack trace.
Log exception file and line since UI's backatrce doesn't include these.
Refactor error logging event handler as a NewRelic\AbstractListener.
Report errors from template rendering too.
Refactor error listener and change retreiving of exception