[AE-158] Specify compatible sketches for each `fqbn:`

[aliphys]

Due to differences in architecture and physical implementation (e.g. no SD slot on the Opta) not all examples in this library are supposed to work with all architectures. In this PR, we use the following scheme to define for which fqbn: which examples should be checked.

include:
  - board:
    additional-sketch-path: |
      - example/SketchA
      - example/SketchB

We define a UNIVERSAL_SKETCH_PATH that includes the location of the test sketches in extras/tests. These tests should work for all platforms. matrix.additional-sketch-paths references the sketches for each fqbn.

[aliphys]

Test sketches in extras/tests compile status as of https://github.com/arduino-libraries/Arduino_UnifiedStorage/pull/13/commits/7c3dd7234b31d8816099a75ab0cb8e171b059ace :

• ✅ arduino:mbed_portenta:envie_m7
• ❌ arduino:renesas_portenta:portenta_c33-> Error: Process completed with exit code 1. ->Log
• ❌ arduino:mbed_opta:opta -> Error: Process completed with exit code 1.-> Log

[aliphys]

Merging https://github.com/arduino-libraries/Arduino_UnifiedStorage/pull/9 should fix compilation issues on C33 and Opta.

[aliphys]

Merging https://github.com/arduino-libraries/Arduino_UnifiedStorage/pull/9 should fix compilation issues on C33 and Opta.

If the compilation issue were fixed, which commit was it? The https://github.com/arduino-libraries/Arduino_UnifiedStorage/pull/9 PR mentioned is still open. I wanted to make sure the compile-sketches workflow is compatible with the changes prior to merging :)

[aliphys]

@per1234 's changes merged into the main branch as part of https://github.com/arduino-libraries/Arduino_UnifiedStorage/pull/16. ✅