Pre-generated MS Visual Studio project & solution files: DELETED

The pre-generated MS Visual Studio project & solution files are no longer available, please use cmake instead (it can generate Visual Studio projects for you).

Pre-generated MS Visual Studio projects used to be the recommended way to build on Windows, but there were some limitations:

• hard to build dependencies, expecially boringssl (deps usually support cmake quite well)
• the nuget-based openssl & zlib dependencies are hard to maintain and update. We've received issues indicating that they are flawed.
• .proto codegen is hard to support in Visual Studio directly (but we have a pretty decent support in cmake)
• It's a LOT of generated files. We prefer not to have too much generated code in our github repo.

See INSTALL.md for detailed instructions how to build using cmake on Windows.