Suppress advertising manifest messages unless verbosity is diagnostic

[Copilot]

Summary: Suppress Advertising Manifest Messages

This PR fixes the issue where advertising manifest messages are displayed during workload install operations. According to the requirements, these messages should only appear when verbosity is set to diagnostic (diag).

What was the problem?

Users were seeing these messages during normal workload install operations:

• "Advertising manifest not updated. Manifest package for {manifest} doesn't exist."
• "Failed to update the advertising manifest {manifest}: {error}."

These messages were being displayed even at normal verbosity levels, which cluttered the output.

Additionally, on unsigned .NET versions, the message "Skipping NuGet package signature verification." was appearing multiple times (once per NuGetPackageDownloader instance).

What changed?

• Added IsDiagnostic() extension method - Returns true only for diagnostic or diag verbosity levels
• Updated WorkloadManifestUpdater - Both error messages are now guarded by the _displayManifestUpdates flag
• Updated command classes - WorkloadInstallCommand, WorkloadUpdateCommand, and WorkloadListCommand now use IsDiagnostic() instead of IsDetailedOrDiagnostic() when creating WorkloadManifestUpdater instances
• Made signature verification message static - Changed _validationMessagesDisplayed flag to static in NuGetPackageDownloader to ensure the message appears only once globally
• Updated tests - Modified existing tests and added new ones to verify the message suppression behavior

Verification:

✅ All 23 WorkloadManifestUpdater tests pass
✅ All 43 WorkloadInstall tests pass (1 pre-existing failure unrelated to this change)
✅ Code review completed with all feedback addressed
✅ CodeQL security scan passed
✅ Build succeeds

Files Modified:

• src/Cli/dotnet/Extensions/CommonOptionsExtensions.cs - Added IsDiagnostic() method
• src/Cli/dotnet/Commands/Workload/Install/WorkloadManifestUpdater.cs - Guarded error messages
• src/Cli/dotnet/Commands/Workload/Install/WorkloadInstallCommand.cs - Changed to IsDiagnostic()
• src/Cli/dotnet/Commands/Workload/Update/WorkloadUpdateCommand.cs - Changed to IsDiagnostic()
• src/Cli/dotnet/Commands/Workload/List/WorkloadListCommand.cs - Changed to IsDiagnostic()
• src/Cli/dotnet/NugetPackageDownloader/NuGetPackageDownloader.cs - Made validation message flag static
• test/dotnet.Tests/CommandTests/Workload/Install/GivenWorkloadManifestUpdater.cs - Updated tests
• test/dotnet.Tests/CommandTests/Workload/Install/GivenDotnetWorkloadInstall.cs - Updated tests

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Advertising manifest messages showing up during install</issue_title>
<issue_description>```
C:\test>dotnet workload install maui ios maccatalyst android --source https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet6/nuget/v3/index.json --source https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-eng/nuget/v3/index.json --source https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-public/nuget/v3/index.json --source https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet7/nuget/v3/index.json --source https://api.nuget.org/v3/index.json

Advertising manifest not updated. Manifest package for microsoft.net.sdk.maui doesn't exist.
Advertising manifest not updated. Manifest package for microsoft.net.workload.emscripten doesn't exist.
Advertising manifest not updated. Manifest package for microsoft.net.sdk.android doesn't exist.
Advertising manifest not updated. Manifest package for microsoft.net.workload.mono.toolchain doesn't exist.

We shouldn't be showing these messages at all. Also during testing admin installs, it looks like we're looking in the wrong place for the advertising manifests (according to Jacques):

C:\test>dotnet workload install maui ios maccatalyst android --from-rollback-file https://maui.blob.core.windows.net/metadata/rollbacks/6.0.4xx-sr3.json --source https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet6/nuget/v3/index.json --source https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-eng/nuget/v3/index.json --source https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet-public/nuget/v3/index.json --source https://pkgs.dev.azure.com/dnceng/public/_packaging/dotnet7/nuget/v3/index.json --source https://api.nuget.org/v3/index.json

Workload(s) 'android ios maccatalyst maui' are already installed.
Skipping NuGet package signature verification.
Failed to update the advertising manifest microsoft.net.sdk.tvos: Failed to extract information from MSI: C:\Users\WDAGUtilityAccount\AppData\Local\Temp\d79c40da-6861-471c-9a26-6de5975949a0\data\Microsoft.NET.Sdk.tvOS.Manifest-6.0.400.15.4.440-x64.msi.
Failed to update the advertising manifest microsoft.net.sdk.macos: Failed to extract information from MSI: C:\Users\WDAGUtilityAccount\AppData\Local\Temp\c5339238-80b9-4907-b3a2-a49cca958a57\data\Microsoft.NET.Sdk.macOS.Manifest-6.0.400.12.3.440-x64.msi.
Failed to update the advertising manifest microsoft.net.sdk.maccatalyst: Failed to extract information from MSI: C:\Users\WDAGUtilityAccount\AppData\Local\Temp\cabd7fce-12a7-411a-ade1-ccf6e05d301d\data\Microsoft.NET.Sdk.MacCatalyst.Manifest-6.0.400.15.4.440-x64.msi.
Failed to update the advertising manifest microsoft.net.workload.mono.toolchain: Failed to extract information from MSI: C:\Users\WDAGUtilityAccount\AppData\Local\Temp\4d113a51-82c4-4772-b944-73723615af0e\data\Microsoft.NET.Workload.Mono.ToolChain.Manifest-6.0.300.6.0.7-x64.msi.
Failed to update the advertising manifest microsoft.net.sdk.android: Failed to extract information from MSI: C:\Users\WDAGUtilityAccount\AppData\Local\Temp\943cb9c7-d6d6-4648-9589-f82993800dca\data\Microsoft.NET.Sdk.Android.Manifest-6.0.300.32.0.442-x64.msi.

<agent_instructions>We should suppress the advertising manifest messages during install unless verbosity is set to diag.</agent_instructions>

## Comments on the Issue (you are @copilot in this section)

<comments>
</comments>

• Fixes Advertising manifest messages showing up during install #26626

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[marcpopMSFT]

@copilot on unsigned .NET versions, we also have a message we include for each manifest which is more than we probably want. I think it's still worth saying it once. Can you reduce the number of times this message is sent to be only once?
Skipping NuGet package signature verification.

[marcpopMSFT]

Testing done: The message only shows up in manifest mode. Confirmed that with this change, I no longer see it but if I do -v:diag, I will still get the messages as expected.

[Copilot]

@copilot on unsigned .NET versions, we also have a message we include for each manifest which is more than we probably want. I think it's still worth saying it once. Can you reduce the number of times...

Fixed in commit b564f6b. Changed the _validationMessagesDisplayed flag from instance-level to static, so the "Skipping NuGet package signature verification." message will only appear once globally across all NuGetPackageDownloader instances during a workload operation.