If config provider has target platform/arch/config selection UI, ensure that's clearly disambiguated from cpptools config selection UI

Feature Request

I'm working on a configuration provider which will internally manage multiple target binaries/configurations/etc itself, and add a status bar item to expose this to users. This configuration provider could either be used by defining a single configuration in the c_cpp_properties.json file, or by allowing cpptools to automatically detect and use it.

In a scenario like this, it would be ideal if cpptools were to hide the default status bar item that it creates to avoid user confusion. I think this could also be useful for configuration providers for build systems such as cmake.

Start with the configuration-provider behavior and c_cpp_properties.json configuration described in the issue, then trace how cpptools exposes its default status bar item. Done means provider-managed platform, architecture, or configuration selection is clearly distinguished and the default cpptools item can be hidden when it would confuse users.