Add CI testing for Windows to Github actions

[kenzieschmoll]

We have had several windows-related bugs in the past related to URIs, differences in permissions, etc. Many of these would have been able to have been caught if we had integration testing on Windows.

Right now adding Windows jobs is blocked on the fact that our CI scripts are shell scripts (see #6324).

In order to add Windows tests, these would need to be converted to Dart scripts (where possible), or copied to a Windows equivalent.

CC @DanTup