@ryanbrandenburg pointed out my change from `. .\activate.ps1` to `.\activate.ps1` in the build from source PR. I've been `.\activate.ps1` and haven't run into any particular issues, however, it's not the recommended way to source due to [scoping](https://docs.microsoft.com/powershell/module/microsoft.powershell.core/about/about_scripts#script-scope-and-dot-sourcing). dotnet/aspnetcore enforces this dot sourcing, so I copied over the script changes here.
Also noticed startvs.cmd had changed so brought that over as well.
Tanay Parikh