symbol server capability for the NuGet package registry symbol packages (.snupkg)
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### Proposal
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Nuget symbol package capability (`.snupkg`) was added in %"14.1"
[Outstanding from that issue is](https://gitlab.com/gitlab-org/gitlab/-/issues/262081#note_608553709):
- Ensure Visual Studio and dotnet-symbol are able to consume these symbol packages correctly.
[The documentation states](https://docs.gitlab.com/ee/user/packages/nuget_repository/#symbol-packages):
> Consuming symbol packages is not yet guaranteed using clients such as Visual Studio or dotnet-symbol. The .snupkg files are available for download through the UI or the API.
A customer has asked if GitLab provides _symbol server support_ (GitLab team members can read more [in the ticket](https://gitlab.zendesk.com/agent/tickets/238997)).
[Reading the "Improved package debugging experience with the NuGet.org symbol server" announcement](https://devblogs.microsoft.com/nuget/improved-package-debugging-experience-with-the-nuget-org-symbol-server/) the final steps detail how to "consume snupgg in Visual studio"
> Under Symbol file (.pdb) locations, add a new symbol server location by selecting the + symbol in the toolbar. Use the following URL https://symbols.nuget.org/download/symbols
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This feature request is to
- document how to configure GitLab as a symbol server
- add the necessary back end support so GitLab can act as a symbol server
## Related issues
related: https://gitlab.com/gitlab-org/gitlab/-/issues/262081
epic