Add support for listing all collectors and their sources

[wizedkyle]

Is your feature request related to a problem? Please describe.
When listing all collectors in a sumo logic tenant it would be good to be able to list all the sources that are associated to that collector or a subset of properties.

Describe the solution you'd like
Ideally another command or an argument on the sumocli collectors list command that allows you to retrieve all the sources for that collector.

Describe alternatives you've considered
You can currently use a combination of commands with for loops in bash/powershell to get this data but it would be nice to have a single command.