Improve logging of unhandled events to reach parity with Python/Java

[misscoded]

Description

#1138 raised the point that the logging of unhandled events in BoltJS is lacking.

Though a PR (#1143) has been opened to address the lack of information around unhandled HTTP requests, there is still a fairly large gap between what is offered by BoltJS and the Python and Java implementations, including but not limited to the option of seeing which events are being sent but have gone unhandled by a listener.

What type of issue is this? (place an x in one of the [ ])

• [ ] bug
• [x] enhancement (feature request)
• [ ] question
• [ ] documentation related
• [ ] example code related
• [ ] testing related
• [ ] discussion

Requirements (place an x in each of the [ ])

• [x] I've read and understood the Contributing guidelines and have done my best effort to follow them.
• [x] I've read and agree to the Code of Conduct.
• [x] I've searched for any related issues and avoided creating a duplicate issue.

Logs, screenshots, screencast, sample project, funny gif, etc.