New sample: Open folder extension

[monamimani]

The Open folder extension in the VSSDK-Extensibility-Samples repository is from vs2017. I am pretty sure things have changed and improved since. I think it would be nice to have an example with the VsixCommunity toolkit if possible. It would be my first extension, it is maybe a bit harder type of extension to do but from my google researches, I couldn't find really any information on how to make one.

I am not sure if it is possible to do what I would like to do. The Cmake "extension" might be a really deep integration, but I would like to try to make an extension to integrate Bazel. there is a VsCode extension but for C++ Visual Studio is still better. ( By the way, I am not an expert in Bazel or Vs extension, just want to try and play with them.)

Thanks