Add support for vcpkg package features

[cursey]

Adds support for vcpkg package features. For example:

[vcpkg]
version = "2021.12.01"
packages = [
    "imgui[docking-experimental,freetype,sdl2-binding,opengl3-binding]",
    "fmt",
    "pegtl",
    "nativefiledialog",
    "spdlog",
    "utfcpp",
    "nlohmann-json",
    "glad[gl-api-30]",
]

I've tested these changes on one of my projects.

[mrexodia]

Thanks a lot for your contribution! I left some minor comments, but if you don’t feel like fixing them I’ll do it in a few days!

[mrexodia]

Thanks a lot!