Multiple docker image architecture support

[dstoft]

Due to ASP.Net Core runtime requiring a different installation when running on different architectures, then a single Dockerfile cannot be used to support multiple architectures. Therefore, for each architecture that has to be supported, the following has to be implemented:

• Dockerfile, which uses a different ASP.Net Core runtime installation.
• Github action, which uses the new Dockerfile
• Dockerhub tag, the Github action will push to a new tag, because it is not possible to build multiple images using different Dockerfiles and then push them to the same docker image tag.

I am removing the current multiple architectures from the Github action now, and then the image will only support amd64 for now. The dockerhub repository: https://hub.docker.com/_/microsoft-dotnet-aspnet contains information about how a dockerfile should look when using other architectures.

[dstoft]

Related issue on the Dashboard-Server-Docker repository: https://github.com/jakobhviid/Dashboard-Server-Docker/issues/21