Added 'hardwareId' support to pluggable discovery

[cmaglie]

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What kind of change does this PR introduce?

Add hardwareId support to the Arduino CLI. The documentation has been updated accordingly.
See #2024 for details and rationale about the change in this PR.

What is the current behavior?

What is the new behavior?

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

No, it adds new features in a backward compatible way.

Other information

Close #2024

[matthijskooijman]

I had a quick look over the PR, looks ok to me (did not look very closely, though). I do wonder: does this really need to be its own field? Would it not also make sense to put this into "properties"? I guess like this it allows defining additional semantics (i.e. same hardwareId -> same board instance), which would at best be part of a written convention if stored in properties?

[codecov]

Codecov Report

Base: 36.67% // Head: 36.76% // Increases project coverage by +0.08% 🎉

Coverage data is based on head (208fc42) compared to base (cc24197).
Patch coverage: 0.00% of modified lines in pull request are covered.

❗ Current head 208fc42 differs from pull request most recent head e34fffb. Consider uploading reports for the commit e34fffb to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2065      +/-   ##
==========================================
+ Coverage   36.67%   36.76%   +0.08%     
==========================================
  Files         228      228              
  Lines       19383    19385       +2     
==========================================
+ Hits         7108     7126      +18     
+ Misses      11442    11431      -11     
+ Partials      833      828       -5     

Flag	Coverage Δ
unit	36.76% <0.00%> (+0.08%)	⬆️

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

Impacted Files	Coverage Δ
arduino/discovery/discovery.go	19.56% <0.00%> (-0.08%)	⬇️
internal/cli/board/list.go	0.00% <0.00%> (ø)
arduino/cores/packagemanager/package_manager.go	68.19% <0.00%> (+0.72%)	⬆️
commands/lib/search.go	92.10% <0.00%> (+3.94%)	⬆️
arduino/monitor/monitor.go	47.36% <0.00%> (+6.31%)	⬆️

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[cmaglie]

Would it not also make sense to put this into "properties"?

Because properties is by definition a set of properties without a defined structure, it may contain anything, even another hardwareId that is not the hardwareId we are defining here. If we reserve a key properties.hardwareId this may potentially create a non-backward compatible change (even if the odds are very low admittedly). Anyway I'd like to leave properties as the territory of discovery developers.

[umbynos]

Mainly cosmetic stuff