Add *.lscache to VisualStudio.gitignore

[wherewhere]

Reasons for making this change

The C# Dev Kit create *.csproj.lscache in new version.

Links to documentation supporting these rule changes

Said by *.csproj.lscache

# This file caches language service data to improve the performance of C# Dev Kit.
# It is not intended for manual editing. It can safely be deleted and will be
# regenerated automatically.
#
# To exclude from version control, add *.lscache to your .gitignore file.

Merge and Approval Steps

• Confirm that you've read the contribution guidelines and ensured your PR aligns
• Ensure CI is passing
• Get a review and Approval from one of the maintainers

[Copilot]

Pull request overview

Adds a new ignore pattern to the repository’s Visual Studio-focused .gitignore rules to prevent C# Dev Kit’s language service cache files (*.csproj.lscache) from being committed.

Changes:

• Add *.lscache ignore entry for VS Code C# Dev Kit cache artifacts.

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