Follow up to #6867 and #10660.

#10660 talks about the MVP, primarily focusing on the restore experience and not the PM UI, PMC & dotnet add package experience.

fyi @JonDouglas

• Design Package Source mapping package experiences for VS Options Dialog #11377
• Design Package Source mapping package installation experiences in VS PM UI #11378
• Design Package Source mapping experiences for dotnet package  #11379
• Design Package Source mapping experiences for listing and adding mappings on the commandline.  #11381
• Design Package Source Mapping experiences for PMC #11383