Generate VisualStudio2019.pkgdef from color xml during build

[JoeRobich]

As a stop gap, the VisualStudio2019,pkgdef was pre-generated for 16.7 builds. It would be better to automate this during the build so that any updates to the color xml will be reflected.

[CyrusNajmabadi]

@JoeRobich do we need this anymore with the decisions around colors in Dev18?

[dotnet-policy-service]

Closing this issue as we've seen no reply to the request for more information. If you are able to get the requested information, please add it to the issue and we will retriage it.