Add detection for boards using CP210x/CH340 bridge.

[jose1711]

This means many ESP32/ESP8266-based dev. boards are now automatically
recognized.

[dhylands]

The issue I have with this is that non-Micropython boards which also use CP310/CH340 chips will also be detected.

What I'd rather see is having something like a .rshell configuration file where you could enter things like PID/VID and have the autoconnect work off of that. Then if you have other boards, you can tweak the settings to work for your own situation.

The configuration could also have things like don't automatically set the clock, and any options which are available via the command line. I wouldn't necessarily put all of that in a the beginning, but knowing the direction to expand in would be useful.

Peter Hinch has a fork where he adds some macro capabilities that I've been meaning to review and merge, and that mechanism should probably be looked at as well.