Add build possibility on windows

[BankaiNoJutsu]

Hello,

This adds the possibility to build on windows, mostly portable. Only the MSVC and SDK dependencies are not portable, which require around 10GB more space than a regular install.

What do you think about adding this?

[Hishiro64]

Yeah I could add this. I ran your branch under a VM to check for portability and a couple of lines using tar need to be swapped to use the 7zr command.

Here's an example of that error when extracting ffmpeg-release-full-shared.7z:

Your tar command might not be pointing to the native windows one, let me know if you can't reproduce it. Build portions don't need to be fully portable, just reasonably reproducible. You should append a section into the README, about any manual steps for the parts that need to be installed onto the system or are too large. As well as any other info needed to create a successful build. I've added a new branch called build-possibility.