Update eda_kicad.py to check for the property "dnp" for components

[FelixGuilbertSavary]

In the function extract_fields, added a loop to check for the property "dnp" in components.

In KiCad 7.0, eeshema has an attribute "Do not populate" when editing a component properties. When enabled, the component will appear with an X overlaid on the component. However, this gets added as a property in the .xml generated by kicad, not a field.

Tested on an in-house schematic. Did not manage to run the tests with tox due to missing Python interpreters.

[set-soft]

It should have an option to make it optional.

I didn't take a look, but the important flag is the one that says the component must be excluded from the BoM. This one isn't the correct flag. The fact that a component isn't soldered doesn't necessarily mean you want to exclude it from the BoM. Yes, I know is common practice, but KiCad has a separated flag to mark this.

[mxa]

That makes total sense. But it seems like the documentation is contradicting.

[set-soft]

You must understand this is a feature that pre-dates the KiCad implementation.
KiCad people implemented it in a different way, they first introduced a flag to exclude from the BoM, and then another to mark the component as not soldered. So KiCad way to mark this, which is newer, is different to what KiCost originally implemented.