Allow use of a dependency helper source file during library detection

[cmaglie]

Please check if the PR fulfills these requirements

See how to contribute

• The PR has no duplicates (please search among the Pull Requests
  before creating one)
• The PR follows
  our contributing guidelines
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)
• UPGRADING.md has been updated with a migration guide (for breaking changes)
• configuration.schema.json updated if new parameters are added.

What kind of change does this PR introduce?

This is a tentative implementation for a strategy to increase the speed of the library discovery phase.
The idea behind this PR is to add a helper file in a library, called arduino_deps.cpp (or arduino_deps.c), whose only purpose is to #include the required dependencies. If the Arduino CLI finds the helper the library detection process is performed only on that file, skipping all the other source files (that may be a lot...).

Advantages:

• It will correctly handle conditional includes (inside ifdefs).
• It must be maintained with the source code, otherwise, the library will fail to compile (differently from the dependencies field in the library.properties that may become outdated if the author is not precise).
• If a library has a lot of source files, the speed-up may be dramatic.

Disadvantages:

• It requires action from lib authors to write an arduino_deps.cpp.
• Writing a correct arduino_deps.cpp may be tricky.
• An incorrect arduino_deps.cpp may result in difficult-to-diagnose "missing include X.h" errors (that could be a workaround by including X.h in the user sketch)

What is the current behavior?

What is the new behavior?

Does this PR introduce a breaking change, and is titled accordingly?

Other information

This may be combined with #2625 for even better performance gain

[codecov]

Codecov Report

Attention: Patch coverage is 43.47826% with 13 lines in your changes missing coverage. Please review.

Project coverage is 67.49%. Comparing base (67eb95a) to head (f593a73).

Files with missing lines	Patch %	Lines
...rnal/arduino/builder/internal/detector/detector.go	53.33%	3 Missing and 4 partials ⚠️
internal/arduino/libraries/libraries.go	25.00%	4 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2758      +/-   ##
==========================================
- Coverage   67.55%   67.49%   -0.07%     
==========================================
  Files         237      237              
  Lines       22358    22375      +17     
==========================================
- Hits        15105    15101       -4     
- Misses       6063     6076      +13     
- Partials     1190     1198       +8     

Flag	Coverage Δ
unit	67.49% <43.47%> (-0.07%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

---

🚨 Try these New Features:

• Flaky Tests Detection - Detect and resolve failed and flaky tests