Motivation

Add a monitor command for interacting with the microcontroller monitor.

Change description

You can test it by:

1. flashing the monitor examples
2. Install this version of arduno-app-cli with task board:install
3. adb shell and run arduino-app-cli monitor

You should see the monitor print from the microcontroller, and you should be able to send in message too.

Additional Notes

• closes Implement the monitor command in app-cli #64

Reviewer checklist

• PR addresses a single concern.
• PR title and description are properly filled.
• Changes will be merged in main.
• Changes are covered by tests.
• Logging is meaningful in case of troubleshooting.