Add package's own `inst/include` with "Generate C/C++ configuration"...

[CGMossa]

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Is your feature request related to a problem? Please describe. Currently, when invoking "R package: Generate C/C++ configuration", every package that is stated in LinkingTo is added in the includePath path via <pkg>/inst/include, in that you run something akin to system.file("include", package = <pkg>).

What would be very nice, is if you tested if the current package had a inst/include, and added that to the includePath in .vscode/c_cpp_properties.json.

I wouldn't add src/include, as that seems excessive, but it is also an option.