Implement makeWin2kImage

[io12]

I think this can be done without vncdotool, tesseract, or expect with Windows 2000's unattended installation feature, and this also makes it easier to configure the install from Nix. I just need to figure out how many times to restart dosbox for the install to finish. And also maybe there's a better way to specify answerFile than a path that is usually created with writeText "answers.ini" (lib.generators.toINI { } { ... })? Having answerFile be the set directly might be easier for the user to specify but less flexible.