VS2019 support

[supcry]

Please add VS 2019 (version 16) to manifest.

[ChrisTorng]

Are there any one install it successfully?
I've tried the method in How to upgrade extensions to support Visual Studio 2019, but failed.
I've tried delete the Prerequisites section, but failed too.

[rolends1986]

Protobuf.vsix.zip

[wnxd]

https://github.com/wnxd/ProtobufLanguageService