Download package symbols if they are packaged as .snupkg #775
Description
For example, Serilog uses .snupkg.
It can be implemented like this:
After downloading the package check if https://www.nuget.org/api/v2/symbolpackage/PACKAGEID/VERSION returns something, and if so download and store it alongside with .nupkg.
On loading we check if a file with extension .snupkg exists, and if so then parse and load .pdb.