Add config option for installing .NET Core runtime in shared mode

Giving the option within the `db-init.sh` initialisation script to install .NET Core Runtime in shared mode would allow for smaller application bundles.

When running `dotnet publish` then bundling within a .zip file, it produces around 200 files and an almost 30MB .zip file. Having the .NET Core Runtime installed on the workers in shared mode allows us to compile with the `--self-contained=false` flag producing around 20 files which bundle into a less than 1MB .zip file.