Make case insensitive matches respect case insensitivity on the root.

[MitchBodmer]

This change addresses #119117 by making the Matcher match root directories case-insensitively when the Matcher is configured to be case-insensitive.

I'm not exactly sure this is the right way to go about this so I'm very open to feedback. The tack I took was to try to limit breaking changes while also fixing the bug.

One problem I hit was that the offending method on the Matcher is actually an extension method. That means it does not have access to the private StringComparison type on the matcher it is extending. I chose to make it a get-only internal property instead of moving the extension method into the matcher type in order to avoid changing the interface.

Another potential issue is that the InMemoryDirectoryInfo is still case-sensitive by default where the typical pattern in this repository has been to make things case-insensitive. Again this was just to avoid any breaking changes.

[Copilot]

Pull Request Overview

This PR fixes case sensitivity handling in the Matcher class so that root directory matching respects the configured case sensitivity settings. Previously, the matcher would handle case sensitivity inconsistently between root directories and subdirectories.

Key Changes:

• Exposes the StringComparison type from Matcher as an internal property to allow extension methods access
• Updates InMemoryDirectoryInfo to accept and use a StringComparison parameter for root directory comparisons
• Adds comprehensive test coverage for both case-sensitive and case-insensitive matching scenarios

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
src/libraries/Microsoft.Extensions.FileSystemGlobbing/tests/FunctionalTests.cs	Adds test methods to verify case-sensitive and case-insensitive root directory matching behavior
src/libraries/Microsoft.Extensions.FileSystemGlobbing/src/MatcherExtensions.cs	Updates extension method to pass matcher's comparison type to InMemoryDirectoryInfo
src/libraries/Microsoft.Extensions.FileSystemGlobbing/src/Matcher.cs	Exposes StringComparison as internal property and updates references
src/libraries/Microsoft.Extensions.FileSystemGlobbing/src/InMemoryDirectoryInfo.cs	Adds constructor overload for StringComparison and updates root directory comparison logic

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[jozkee]

Thanks.