Separate into `.install` and `.portable` versions

[rollingmoai]

As of https://github.com/neovim/neovim/releases/tag/v0.7.0, MSI installers now exist. This means the chocolatey packages should now be separated into .install and .portable versions for the MSI and zip. See: What is the difference between packages no suffix as compared to *.install *.portable?

[tricktux]

Received! Will look into it.