[FEATURE] raspberrypi pico w/2/2w firmware flashing automation with make flash

### Is your feature request related to a problem? Please describe.

* For now in order to flash rPI-Pico(-W/-2/-2W) we need to manually press Boot button on USB attach then copy-paste firmware file.
* That blocks automation testing.

### Describe the solution you'd like

* Use `make flash` to have firmware flashed and ready for runtime testing.
* Enable full automation of firmware flashing.

### Describe alternatives you've considered

@keever50 reported that `picotool` (something like `esptool` for ESP32) can be used to flash firmware but still requires manual Boot button interaction, and PlatformIO can switch to BootROM by some magic sequence. That may indicate flashing automation should be possible.

### Verification

- [x] I have verified before submitting the report.