add command line switch to point to existing dotnet installation installed in a non-standard way

[cowardlycamper32]

I have several dotnet installations for development purposes through scoop a windows package manager and VS cannot detect the correct version of dotnet. I believe this will allow people to play the game easier, especially through launchers, as they can just pass a command line switch with the correct dotnet path instead of having to make a batch script or shell script using the dotnet command.