Add Chrome debugging support

[ono-max]

It's sometimes hard for users to see big backtrace information in the terminal. To solve the problem, Chrome Devtools Frontend is one solution.

Screen.Recording.2021-09-28.at.21.16.06.mov

How to use

1. Run with rdbg and enter open chrome.
   If you want to run it from the command line, you can use rdbg --open=chrome.
2. Enter the URL which is outputted in the terminal in Google Chrome.
   In the following example, open devtools://devtools/bundled/inspector.html?ws=127.0.0.1:65124.

$ rdbg target.rb
[1, 4] in target.rb
=>   1| a=1
     2| b=1
     3| c=1
     4| d=1
=>#0	<main> at target.rb:1
(rdbg) open chrome    # command
DEBUGGER: wait for debugger connection...
DEBUGGER: Debugger can attach via TCP/IP (["#<Addrinfo: 127.0.0.1:65124 TCP>"])
DEBUGGER: Enter the following URL in Chrome:

devtools://devtools/bundled/inspector.html?ws=127.0.0.1:65124

3. Click the Sources plane.

For more information about how to use Chrome debugging, you might want to read here

Acknowledgement

Many people helped me to create this PR.

• Sasada-san gave me the idea that to use Chrome for the debugger. Thanks to the DAP server that he created, I was able to write several codes smoothly.
• I wrote several codes based on geoffreylitt/ladybug: Visual Debugger. The author also advised me in email.
• I understand the basics of Chrome Devtools Protocol through creating a prototype in node.js. Thanks to the great help of the chrome-remote-interface team, I was able to do it.
• I learned the basic concepts about the WebSocket from the following URLs.
  • https://developer.mozilla.org/en-US/docs/Web/API/WebSockets_API/Writing_WebSocket_servers
  • https://github.com/pusher/websockets-from-scratch-tutorial
  • https://developer.mozilla.org/en-US/docs/Web/API/WebSockets_API/Writing_WebSocket_server
  • https://www.honeybadger.io/blog/building-a-simple-websockets-server-from-scratch-in-ruby/

[ono-max]

Thanks, I'll refactor the WebSocket logic.