Re-add option to set the default baud rate

[CraigSiemens]

I'm using this through using the vscode-arduino extension and filed an issue for this in that repo as well microsoft/vscode-arduino#1703.

The serial monitor defaults to using the highest baud rate in the list. When working with devices that only support lower rates, the setting has to be manually changed for run.

Previously vscode-arduino had a setting for the default baud rate but it looks like it was lost in the transition to this repo.

• Originally added
  add arduino.defaultBaudRate option vscode-arduino#620
• Removed when switching to this extension
  Modify to use standalone Serial Monitor Extension vscode-arduino#1577
  microsoft/vscode-arduino@bb0bcd4

[gcampbell-msft]

@CraigSiemens Thanks for the suggestion. I'll make sure this gets put on the backlog, and we will track it's popularity by the number of up-votes on the initial post, thanks!

[Ares9323]

I found a temporary workaround if you are interested