Remove Developer Mode / Admin requirement for Windows install by using junctions

I can and do use WSL, but it's a VM and I'd like to be able to use krew on my host as well (especially since WSL can be finicky and unstable) without convincing the enterprise security folks to turn on Developer Mode for all the developers that I'm trying to enable this for.

I'm not volunteering to do this work, but throwing it out there in response to this comment https://github.com/kubernetes-sigs/krew/issues/631#issuecomment-1651531922

Several CLI applications have undergone a similar shift from symlinks over to junctions on Windows such as:

• fnm - see https://github.com/Schniz/fnm/pull/519
• volta has an open PR https://github.com/volta-cli/volta/pull/1552

In the meantime I'm just not using krew on Windows, set up a script to copy the most important plugins over.