Migrate Nina firmwares to the new plugin system

[umbynos]

We need to update the generator.py to publish all the 5 4 boards based on nina:

• arduino:samd:mkrwifi1010
• arduino:samd:nano_33_iot
• arduino:samd:mkrvidor4000 (EOL)
• arduino:megaavr:uno2018
• arduino:mbed_nano:nanorp2040connect

All the boards uses the same plugin but different loader tools.
The arduino:mbed_nano:nanorp2040connect uses rp2040tools
The arduino:megaavr:uno2018 uses avrdude
The remaining uses bossac.