Added 'label' and 'properties' fields in board -w command (json output)

[cmaglie]

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• 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)

What kind of change does this PR introduce?
Adds all the information available from discoveries to the board -w --format json output, in particular the label and properties fields that are missing from the output.

What is the current behavior?

$ arduino-cli board -w --format json
{
  "type": "add",
  "address": "/dev/ttyACM0",
  "protocol": "serial",
  "protocol_label": "Serial Port (USB)",
  "boards": [
    {
      "name": "Arduino Uno",
      "fqbn": "arduino:avr:uno"
    }
  ]
}

What is the new behavior?

$ arduino-cli board -w --format json
{
  "type": "add",
  "address": "/dev/ttyACM0",
  "label": "/dev/ttyACM0",
  "protocol": "serial",
  "protocol_label": "Serial Port (USB)",
  "properties": {
    "pid": "0x0043",
    "serialNumber": "754393237353511051D2",
    "vid": "0x2341"
  },
  "boards": [
    {
      "name": "Arduino Uno",
      "fqbn": "arduino:avr:uno"
    }
  ]
}

Does this PR introduce a breaking change, and is titled accordingly?
No

[codecov]

Codecov Report

Merging #1845 (7d3217d) into master (c756472) will decrease coverage by 0.00%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master    #1845      +/-   ##
==========================================
- Coverage   36.26%   36.26%   -0.01%     
==========================================
  Files         232      232              
  Lines       19496    19498       +2     
==========================================
  Hits         7071     7071              
- Misses      11594    11596       +2     
  Partials      831      831              

Flag	Coverage Δ
unit	36.26% <0.00%> (-0.01%)	⬇️

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

Impacted Files	Coverage Δ
cli/board/list.go	0.00% <0.00%> (ø)

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[per1234]

Thanks Cristian!