add Arduino-CI + prepare unit tests

[RobTillaart]

Based upon - https://github.com/marketplace/actions/arduino_ci

Goal
The goal of continuous integration and unit testing is to have a set of automated actions to improve the quality and consistency of the code and its interface. To reach this goal two major steps exist

1. Automatic compilation of all examples on different platforms this PR
2. Automatic unit tests disabled

The automatic build of examples shows

• the library compiles
• the examples compile

The automatic compilation is done for (to be expanded in the future)

• uno
• leonardo
• due
• zero

Unit Tests disabled
The unit test is disabled by altering its extension. The reason is that the mocking / including of the complete Arduino environment is not complete yet. An issue has been raised for this and equivalent libraries - Arduino-CI/arduino_ci#251

Notes

• Code of library has not changed.
• Option to add badges in the readme.md file like below to show status of library

(these are just an example)

[RobTillaart]

update
This PR solves #182 a new issue for updating the unit tests could be made.

[milesburton]

Let me know if you're ready to merge, looks like a good initial addition

[RobTillaart]

I'm ready,
already preparing the next step today, the Arduino-lint workflow .
I have about 40 fails in 120 libraries so I'm busy for a few days 😎 (also means ~80 are OK)

[RobTillaart]

Got some first feedback from the Arduino-lint action for the Dallas Temp lib
See - https://github.com/RobTillaart/Arduino-Temperature-Control-Library/runs/2686896760?check_suite_focus=true

• Easy fix is adding a license file ==> MIT (you did an inquiry some time ago)
• Filename is a too long will be a more problematic thing, have to think about that

[RobTillaart]

Created an issue (question) about the filename - arduino/arduino-lint#178