Add "Copy for Powershell" for Windows/Powershell users

Currently we have 2 options: for our CONSOLified docs: `Copy as cURL` and `View in Console`. The former is easy to understand for our *nix users and the latter is easy to understand for anybody running Kibana, but neither really helps our Windows users understand/build/automate queries in their platform. That is, you can download `curl` for Windows, but that's an extra several steps to hunt it down, making the getting started experience not so great. Also, there's a Powershell alias for `curl` but it's not compatible with the "standard" *nix `curl` command for the vast majority of examples that show up in our docs.

It'd be nice to have a "native" `Copy for Powershell` type of option for Windows users which copies the appropriate Invoke-WebRequest and the appropriate IRM parameters.

/cc @russcam @Mpdreamz