XRAY-156685 - Nuget native support

[Phavya-jfrog]

• The pull request is targeting the dev branch.
• The code has been validated to compile successfully by running go vet ./....
• The code has been formatted properly using go fmt ./....
• All static analysis checks passed.
• All tests have passed. If this feature is not already covered by the tests, new tests have been added.
• Updated the Contributing page / ReadMe page / CI Workflow files if needed.
• All changes are detailed at the description. if not already covered at JFrog Documentation, new documentation have been added.

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Add native repository resolution for NuGet in jf ca — no jf nuget-config yaml.

NuGet resolution priority:

1. Detect .NET CLI vs legacy NuGet CLI from the project's own files ( in .csproj → dotnet; packages.config → legacy nuget)
2. Ask that tool for its own configured sources — we never read a NuGet.Config file ourselves, we just trust the CLI's output:
   • .NET CLI → dotnet nuget list source → resolves from
     ~/.nuget/NuGet/NuGet.Config (plus any project-level nuget.config)
   • legacy CLI → nuget sources List → resolves from
     ~/.config/NuGet/NuGet.Config (plus any project-level nuget.config)
     Match the enabled source whose host equals the configured 'jf c' server.
3. Clear error if none match, naming the right Set Me Up tab (.NET vs NuGet)