Imagemagick for ARM64

[virzak]

The installation be from: https://imagemagick.org/archive/binaries/ImageMagick-7.1.1-16-Q16-HDRI-arm64-dll.exe

[bdukes]

It looks like the ability for a package to expose ARM installation URLs is not yet supported in Chocolatey: chocolatey/choco#1803. Once that's defined, it will be simple to add to this package. Thanks!