Use powershell for download function for Windows

[JeffBezanson]

Fixes #19526.

[oxinabox]

It it worth this having a fallback to urlmon (or even to ie.exe) for purposes of making it work on Windows Vista and earlier?

[JeffBezanson]

My understanding is that we only support windows 7+.

[pkofod]

My understanding is that we only support windows 7+.

relevant part of windows readme for those curious where it says that:

https://github.com/JuliaLang/julia/blob/9cdd88789604096999d4b2c1935d18aee4ade895/README.windows.md#binary-distribution

[JeffBezanson]

I'll just merge this and we'll see how it goes.

[davidanthoff]

I think one potential problem with this might be corporate machines that have powershell disabled via group policy... I also think that Windows Nano Server doesn't ship with Powershell by default. Not sure there are enough users in any of these categories to matter, but this will probably not work everywhere.

[ihnorton]

I think one potential problem with this might be corporate machines that have powershell disabled via group policy

https://stackoverflow.com/questions/49061971/is-it-possible-to-stop-julia-from-using-powershell-on-windows-7

[Petr-Hlavenka]

I'm very positive to have only one download function in base and use it everywhere - but I'd also like a optional hook-in mechanism such that the user might customize it for some corner cases - on clusters, in corporate environment, etc... The custom routine might ask e.g. a linux machine by ssh to download it for you to a shared storage and than copy it from that place to the destination place.

[nalimilan]

Julia provides this hook-in mechanism by default: just replace Base.download, and all code will use your custom version.