Support downloading nuget nuspec manifest[^1]. This is useful for
renovate because it uses this api to find the corresponding repository
- Store nuspec along with nupkg on upload
- allow downloading nuspec
- add doctor command to add missing nuspec files
[^1]:
https://learn.microsoft.com/en-us/nuget/api/package-base-address-resource#download-package-manifest-nuspec
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Co-authored-by: KN4CK3R <admin@oldschoolhack.me>