Expose a golang package to handle FQBNs

[cmaglie]

Describe the request

Extract the functions to parse FQBN out of internal and make a proper golang package.
This package may turn out useful to implement other tools.

Describe the current behavior

I had to rewrite FQBN parser on my own.

Arduino CLI version

nightly

Operating system

N/A

Operating system version

N/A

Additional context

No response

Issue checklist

• I searched for previous requests in the issue tracker
• I verified the feature was still missing when using the nightly build
• My request contains all necessary details