[breaking] Allow setting extra paths for build-cache

[cmaglie]

Please check if the PR fulfills these requirements

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

What kind of change does this PR introduce?

Allows to specify extra paths for build-cache to look for already build artifacts if they are not found in the default build-cache dir.

What is the current behavior?

What is the new behavior?

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

Yes.

Other information

Fix #2611

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 75.71429% with 17 lines in your changes are missing coverage. Please review.

Project coverage is 70.30%. Comparing base (dc13ef6) to head (8bdda04).

Files	Patch %	Lines
internal/arduino/builder/core.go	66.66%	9 Missing and 2 partials :warning:
commands/service_compile.go	73.91%	4 Missing and 2 partials :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #2612 +/- ## ========================================== + Coverage 70.26% 70.30% +0.03% ========================================== Files 222 222 Lines 21262 21304 +42 ========================================== + Hits 14940 14977 +37 - Misses 5147 5151 +4 - Partials 1175 1176 +1 ``` | [Flag](https://app.codecov.io/gh/arduino/arduino-cli/pull/2612/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=arduino) | Coverage Δ | | |---|---|---| | [unit](https://app.codecov.io/gh/arduino/arduino-cli/pull/2612/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=arduino) | `70.30% <75.71%> (+0.03%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=arduino#carryforward-flags-in-the-pull-request-comment) to find out more.

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