Build and debug C++ with cl without needing to start vscode from the developer prompt

[rickywei]

[sean-mcmanus]

If you want to build with cl.exe, you need to run it from the developer command prompt. We had an issue tracking removing that requirement, but I'm not able to locate it, so we could use this issue track that.

[Colengms]

A user proposed the following solution: microsoft/vscode-docs#4437

The cppbuild task provider could configure the environment, perhaps using code currently in CMake Tools to find the devbat script, or through a setting that indicates which version/install of VS to get the script from.