feat: allow boards to change debug support via FQBN options

[pillo79]

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What kind of change does this PR introduce?

"debug.executable" must be present AND non-empty for debugging to be supported, allowing board overrides. Also, use the same logic in the details view and in the actual debug command implementation.

What is the current behavior?

Debug support is enabled if any of the txt files define a key named debug.executable, regardless of its contents, preventing overrides by board and/or menu options

What is the new behavior?

"debug.executable" must be present AND non-empty for debugging to be supported, allowing board overrides. Also, use the same logic in the details view and in the actual debug command implementation.

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

No, it is backwards compatible (all cores using debug define the key to a valid string, cores without debug never define the key).

Other information

Tested with Arduino Nano ESP32 package.
Original platform.txt already contains:

debug.executable={build.path}/{build.project_name}.elf 

Lines added to boards.txt:

nano_nora.debug.executable=   
nano_nora.menu.USBMode.hwcdc.debug.executable={build.path}/{build.project_name}.elf   

• Output from arduino-cli board details -b arduino-git:esp32:nano_nora --format json does not include debugging_supported key.
• Output from arduino-cli board details -b arduino-git:esp32:nano_nora:USBMode=hwcdc --format json includes "debugging_supported": true.

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[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (4bf81fd) 67.28% compared to head (957ceae) 67.30%.

Files	Patch %	Lines
commands/debug/debug_info.go	0.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2436      +/-   ##
==========================================
+ Coverage   67.28%   67.30%   +0.01%     
==========================================
  Files         210      210              
  Lines       20568    20573       +5     
==========================================
+ Hits        13840    13846       +6     
+ Misses       5588     5587       -1     
  Partials     1140     1140              

Flag	Coverage Δ
unit	67.30% <88.88%> (+0.01%)	⬆️

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[cmaglie]

Thanks for the PR @pillo79!

After merging #2435 the "debugging supported" is much more complex to determine and it depends also on the programmer selected.

We agreed that the "debugging supported" should no longer be a property of the board.
You can determine if debugging is supported by calling GetDebugConfig (if the call succeeds then the debugging is supported).