Include XPCCs generated paths for VSCode C++ includePath

[se-bi]

This extends the "includePath" list in .vscode/c_cpp_properties.json
when using the ::communication:xpcc:generator in combination with this ::ide:vscode
by e.g. this entry: "${workspaceFolder}/generated/xpcc/".

Points open for discussion:

• How to get rid of that message, because it does not matter(?):
  [WARNING] lbuild.node: Module 'modm:ide:vscode' accessing 'modm:communication:xpcc:generator:path' without depending on 'modm:communication:xpcc:generator'!
• The os.makedirs is kind of a workaround to create that empty directory structure here.
  But if the workspace is opened in VS Code with that directory missing, it does not get over it.
  With the directory existing but files not (later created with scons) it gets along with that later.
• This itself is also kind of a workaround since this is generated with scons and there added to the includePath for the actual build
• Reduced number of XPCC example does not make it easy to test.
  • and btw. with the avr example it seems to reveal that there are some includes not properly..?
    The platform/gpio/port.hpp has an include for math/utils/bit_operation.hpp which is not generated/copied by LBuild

[salkinium]

I'll look into it next weekend. I saw that the VSCode Debug plugins got more features, so I'll probably need to adapt this anyways again.