This allows you to list and explore connected USB devices. It
only stubs out the methods to communicate to endpoints. That will
come in a follow up once TinyUSB has it. (It's in progress.)
Related to #5986
This also removes the need to pin share because we don't use the
status LED while user code is running.
The status flashes fallback to the HW_STATUS LED if no RGB LED is
present. Each status has a unique blink pattern as well.
One caveat is the REPL state. In order to not pin share, we set the
RGB color once. PWM and single color will be shutoff immediately but
DotStars and NeoPixels will hold the color until the user overrides
it.
Fixes#4133
Scott Shawcroft
microDev
Diego Elio Pettenò
Lucian Copeland
arturo182