Add Protobuf serialization example from blog post

[uilianries]

• Use CMakeToolchain + CMakeDeps + cmake_layout instead of legacy cmake generator
• Update Protobuf to the latest version available in Conan Center
• Use Protobuf syntax version 3 instead of 2 (legacy).
• Include protobuf as tool requirement too, to make possible to parse .proto file
• Use protobuf targets instead of old CONAN_PKG

closes #102

[CLAassistant]

All committers have signed the CLA.

[uilianries]

As always, Windows opposes to accept my PR. I'll check at home, as I don't have access to a Windows machine right now.

[uilianries]

Fixed Windows build!