Add internal build support for appliance images

[lbussell]

Parent issue: https://github.com/dotnet/dotnet-docker-internal/issues/6782

All appliance images must now support building with internal builds from Azure DevOps. Images can follow the existing patterns present in other .NET Dockerfiles and templates.

For more context see #6244 and https://github.com/dotnet/dotnet-docker-internal/issues/6782.