Added external programmer support

[cmaglie]

This PR add support for

• list supported programmers for a board:

$ ./arduino-cli upload --fqbn arduino:avr:uno --programmer list
ID                     Programmer Name                Platform         
avrispmkii             AVRISP mkII                    arduino:[email protected]
jtag3                  Atmel JTAGICE3 (JTAG mode)     arduino:[email protected]
jtag3isp               Atmel JTAGICE3 (ISP mode)      arduino:[email protected]
arduinoisp             ArduinoISP                     arduino:[email protected]
usbGemma               Arduino Gemma                  arduino:[email protected]
avrisp                 AVR ISP                        arduino:[email protected]
parallel               Parallel Programmer            arduino:[email protected]
buspirate              BusPirate as ISP               arduino:[email protected]
arduinoasispatmega32u4 Arduino as ISP (ATmega32U4)    arduino:[email protected]
usbasp                 USBasp                         arduino:[email protected]
atmel_ice              Atmel-ICE (AVR)                arduino:[email protected]
usbtinyisp             USBtinyISP                     arduino:[email protected]
arduinoisporg          ArduinoISP.org                 arduino:[email protected]
stk500                 Atmel STK500 development board arduino:[email protected]
arduinoasisp           Arduino as ISP                 arduino:[email protected]

• upload with external programmer using the command line:
  arduino-cli upload .... -P programmer-id

• burn bootlader:
  arduino-cli upload --fqbn ... --burn-bootloader (changed as per @ubidefeo suggestion)
  arduino-cli burn-bootloader --fqbn ....

Another improvement of this PR is that it makes the --port parameter mandatory only when really needed in upload patterns.

Missing:

• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

[ubidefeo]

I would advice to keep the --burn-bootloader as its own command, hence burn-bootloader as a command to arduino-cli

example:
arduino-cli burn-bootloader --fqbn arduino:samd:nano_33_iot -p atmel_ice -v

upload, on the other hand, should be related to "uploading" or "programming" a firmware generated by the Arduino workflow

[cmaglie]

I would advice to keep the --burn-bootloader as its own command, hence burn-bootloader as a command to arduino-cli

Agreed, I'll fix this out.

[rsora]

Excellent!