Simple serial USB example

../examples/platformio/example1

This is simple example with USB CDC-ACM device. After connecting to host it will be detected and panel will display this message:

on connect message:

https://matrix-panel.esp32.eu.org/_static/example1/image1.png

on disconnect message:

https://matrix-panel.esp32.eu.org/_static/example1/image2.png

hello world text from serial monitor or terminal (example):

https://matrix-panel.esp32.eu.org/_static/example1/image3.png