Add CI workflows for compilation testing, spell check, and formatting check

[per1234]

These GitHub Actions workflows will:

• Compile all example sketches for one board of each significant type of each active official boards platform
• Check for commonly misspelled words in all files
• Check for compliance with the established code formatting standard for Arduino sketches

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NOTE: The failure of the Compile Examples workflow run is due to legitimate compilation errors.

These should be resolved by either:

• Fixing the bugs

Or

• Documenting that the sketch is not compatible with that boards platform and then excluding that sketch from being compiled for the board in the workflow.

That work is out of scope for this PR.

• Uno WiFi Rev2
  • examples/11.ArduinoISP/ArduinoISP: reference to 'SPISettings' is ambiguous
  • https://github.com/arduino/arduino-examples/runs/1019157046?check_suite_focus=true#step:4:250
  • There's no documentation that this board is not compatible with the sketch.
• Nano 33 BLE
  • examples/11.ArduinoISP/ArduinoISP: reference to 'SPISettings' is ambiguous
  • https://github.com/arduino/arduino-examples/runs/1019157077?check_suite_focus=true#step:4:250
• Portenta H7
  • examples/06.Sensors/Memsic2125, examples/06.Sensors/Ping: undefined reference to 'pulseIn'
    • https://github.com/arduino/arduino-examples/runs/1019157086?check_suite_focus=true#step:4:178
  • examples/11.ArduinoISP/ArduinoISP: reference to 'SPISettings' is ambiguous
  • https://github.com/arduino/arduino-examples/runs/1019157086?check_suite_focus=true#step:4:257
• Due
  • examples/02.Digital/toneKeyboard, examples/02.Digital/toneMelody, examples/02.Digital/toneMultiple, examples/02.Digital/tonePitchFollower: 'tone' was not declared in this scope
  • https://github.com/arduino/arduino-examples/runs/1019157115?check_suite_focus=true#step:4:61

[silvanocerza]

PR approved but I have a question nonetheless, why are we using astyle instead of something else like clang-format?

[per1234]

why are we using astyle

I chose it because astyle is the tool used by the Arduino IDE's Tools > Auto Format feature and also used by the manually run formatter script.

Although the formatter configuration defined by examples_formatter.conf does add a few additional things, my primary goal is for the examples to always be compliant with the formatting style established by the default auto format settings. It seems like this can most easily be achieved by using the same formatter tool for the check. My concern with using a different formatter tool is that there might be some subtle differences in the formatting. I haven't investigated this at all though.

I'm certainly open minded about other tools, but I'll ask you the opposite question: Why not use astyle?

[silvanocerza]

Just a matter of personal preference in this case, I've always used clang-format with C++ so I feel comfortable using that instead of astyle.

If it's already used by the Arduino IDE I'm fine with it.

[ubidefeo]

@silvanocerza I remember a while back (actually one of my first interactions with @per1234 ) I was trying to get clang-format to get the format right for Arduino IoT Cloud examples in SublimeText. I ended up trying so many things and failing that in the end I embraced Per's instructions and went with it. Also, I have since removed every bit of knowledge about how to do that and I'm a happier person :D