Add feed for dotnet maui 9.0.111.

[LoopedBard3]

Add feed for dotnet maui 9.0.111. Copies the feed from dotnet/maui#31864.

[Copilot]

Pull Request Overview

This PR adds a new NuGet package source feed for .NET MAUI 9.0.111, enabling access to packages from the specific Azure DevOps feed required for this version.

• Adds a new NuGet package source for .NET 9 MAUI with the key "darc-pub-dotnet-maui-7c4f71ad"
• Includes a descriptive comment to identify the purpose of the new feed
• Follows the existing pattern used for other MAUI version feeds in the configuration

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