Breaking changes in .NET 8 Docker images about fotostoriomicroservices

[DavidAJohn]

All of the projects that had been updated to target .NET 8 so far have now been changed so that they expose port 8080 within Docker.

The changes required were quite simple - just a change of port in each Dockerfile and an update to the docker-compose.override.yml file so each updated project uses port 8080.

While updating the Dockerfiles, I took the opportunity to use the new 'app' user which has been added to improve container security by avoiding running everything as root.

I also added a couple of lines where the build configuration is passed as an ARG in the build and publish steps. This is straight out of the Dockerfile generated by one of the new .NET 8 templates with Docker support added.

The gateway projects also needed the Ocelot config files updated to refer to containers running on port 8080.

I'll also do the same with the remaining projects as and when they get updated to .NET 8.