auto-generate IntelliSense configuration trashes unrelated sections in .vscode/c_cpp_properties.json

[the-moog]

I have to use an [env] section in c_cpp_properties.json to allow cross platform and build location independent builds (Windows/Linux/Jenkins/Make etc). I have more than one target depending on the build platform.
When arduino.disableIntelliSenseAutoGen is not set 'true' the generator trashes the existing configuration whereas it should only touch keys it knows about.

If you don't enable it then, as the project is large and complicated definitions are not passed to IntelliSense and it then spews errors.

Suggestions:
Alter Intellisense to allow reading defines from a file, and have the autogenerator make that file, that way the config file does not need to be changed.
Rather than re-writing the whole file, perhaps it should generate a new section for the auto-generated target? e.g. target[autogen].

Also, I noted that if you upgrade the VSCode Arduino extension it defaults the setting rather than keeping the previous. Hence why I found this issue!