Create Restore Bar logger in Package Manager UI

[donnie-msft]

Bug

Fixes: NuGet/Home#13407

Description

Informational messages are no longer logged to the RestoreBar (InfoBar / Gold Bar / Yellow bar) in NuGet's Package Manager UI.

• Create a new logger that specifically models the RestoreBar's logger where only Warning level or higher are displayed.
  • Maintains the adapter approach for INuGetProjectContext.
• Output Pane continues to show Info level, informational logging.
  • For example, CACHE https://api.nuget.org/v3/vulnerabilities/index.json is shown in Output Pane but no longer in the Restore Bar.

Side effects

• Reduces screen flicker which occurred from briefly showing and hiding the Restore Bar for HTTP status (GET / OK / CACHE).

Future considerations

• Suggest that the next step be to look into simplifying the logging overall.
• Possibly LoggerBase and LoggerAdapter can be merged as there's a lot of overlap.
• INuGetProjectContext representing a project and a logger isn't a great abstraction. The separation of concerns could be improved.

PR Checklist

• Meaningful title, helpful description and a linked NuGet/Home issue
• Added tests
• Link to an issue or pull request to update docs if this PR changes settings, environment variables, new feature, etc.

[Copilot]

Pull Request Overview

This PR introduces a new RestoreBarLogger to ensure that only log messages of Warning level or higher are displayed in NuGet's Package Manager UI Restore Bar, addressing the bug described in NuGet/Home#13407.

• Added unit tests for RestoreBarLogger behavior.
• Updated PackageRestoreBar.xaml.cs to use RestoreBarLogger instead of LoggerAdapter.
• Implemented RestoreBarLogger to forward only selected log levels to the underlying INuGetProjectContext.

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
test/NuGet.Clients.Tests/NuGet.PackageManagement.UI.Test/Utility/RestoreBarLoggerTests.cs	Added tests verifying that only Warning level and above messages are logged.
src/NuGet.Clients/NuGet.PackageManagement.UI/Xamls/PackageRestoreBar.xaml.cs	Updated logger initialization to use RestoreBarLogger.
src/NuGet.Clients/NuGet.PackageManagement.UI/Utility/RestoreBarLogger.cs	Introduced RestoreBarLogger with filtering based on verbosity level.