Add a process to manage and query a Registry of Registries

[kilasuit]

Summary of the new feature / enhancement

As there is more movement to Module/Script Authors to host their own trusted package sources over ones like the PowerShellGallery, it would be great if we could have a central source file where we can add our package sources to for others to discover them & more importantly to be able to update from if we choose to move sources to other providers.

Proposed technical implementation details (optional)

I'd suggest that we have some form of store for package sources and a cmdlet that can return information from this that can then be Piped to Register-PSResourceRepository