Input Formatting

In a similar way to output formats in #166, we should consider input formatting.
What can we do in System.CommandLine that allows us to pipe the output of objects from one program into another without requiring PowerShell?
E.g. Allow a user to run:
`GetADUsers.exe /Group PowerUsers /OutputFormat json | AddUsersToAzureGroup /InputFormat json`
Input formats could be handled for command line arguments or even via the console stdin.
There is also the concept of providing command line arguments from different providers such as files, command line, environment variables... etc.