legacy: Arduino preprocess subroutine refactorization (part 1)

[cmaglie]

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• The PR has no duplicates (please search among the Pull Requests
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• 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 PR is a try to split the bigger PR #2147 into smaller pieces to allow an easier review process.

What is the current behavior?

What is the new behavior?

No changes

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

No

Other information

[codecov]

Codecov Report

Patch coverage: 78.16% and project coverage change: -0.10 ⚠️

Comparison is base (493fa83) 62.93% compared to head (a3ae9d8) 62.84%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2186      +/-   ##
==========================================
- Coverage   62.93%   62.84%   -0.10%     
==========================================
  Files         223      220       -3     
  Lines       19537    19476      -61     
==========================================
- Hits        12295    12239      -56     
+ Misses       6155     6149       -6     
- Partials     1087     1088       +1     

Flag	Coverage Δ
unit	62.84% <78.16%> (-0.10%)	⬇️

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

Impacted Files	Coverage Δ
legacy/builder/create_cmake_rule.go	8.99% <0.00%> (+0.18%)	⬆️
legacy/builder/preprocess_sketch.go	0.00% <0.00%> (ø)
legacy/builder/types/context.go	97.53% <ø> (ø)
legacy/builder/utils/utils.go	50.39% <ø> (-4.35%)	⬇️
arduino/builder/sketch.go	52.80% <30.76%> (-4.83%)	⬇️
legacy/builder/ctags_runner.go	68.75% <62.50%> (-9.30%)	⬇️
legacy/builder/container_add_prototypes.go	77.77% <85.71%> (+9.35%)	⬆️
arduino/builder/cpp.go	91.42% <91.42%> (ø)
legacy/builder/builder.go	86.51% <100.00%> (-4.11%)	⬇️
legacy/builder/ctags/ctags_has_issues.go	98.62% <100.00%> (-0.02%)	⬇️
... and 3 more

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