Fix IDN Test on Linux

[tarekgh]

Fix #115087

[Copilot]

Pull Request Overview

This pull request fixes the IDN tests on Linux by updating test file references and adjusting ICU version branching to correctly map to the appropriate Unicode IDNA test data.

• Updated documentation in Unicode_15_1_IdnaTest.cs to reference the correct test data file.
• Added a new Unicode_15_0_IdnaTest.cs test file.
• Updated Factory.cs to adjust ICU version comparisons for proper test file selection.

Reviewed Changes

Copilot reviewed 5 out of 7 changed files in this pull request and generated no comments.

File	Description
Unicode_15_1_IdnaTest.cs	Updated comment reference to point to the Unicode 15.1 test data file.
Unicode_15_0_IdnaTest.cs	Added new test file for Unicode 15.0.
ReadMe.txt	Added documentation for Unicode 15.0 test data.
Factory.cs	Modified version checks to map ICU versions to the correct IDNA test data files and test class.

Files not reviewed (2)

• src/libraries/System.Runtime/tests/System.Globalization.Extensions.Tests/NlsTests/System.Globalization.Extensions.Nls.Tests.csproj: Language not supported
• src/libraries/System.Runtime/tests/System.Globalization.Extensions.Tests/System.Globalization.Extensions.Tests.csproj: Language not supported

Comments suppressed due to low confidence (2)

src/libraries/System.Runtime/tests/System.Globalization.Extensions.Tests/IdnMapping/Data/Factory.cs:34

• Ensure that the branching logic for ICUVersion using Version(72, 1, 0, 4) is adequately covered by tests, especially around the boundary conditions distinguishing between Unicode 15.1 and 15.0 test file selections.

else if (PlatformDetection.ICUVersion >= new Version(72, 1, 0, 4))

src/libraries/System.Runtime/tests/System.Globalization.Extensions.Tests/IdnMapping/Data/Factory.cs:75

• Verify that the conditional branch for returning a Unicode_15_1_IdnaTest is covered by unit tests, particularly when ICUVersion is exactly Version(72, 1, 0, 4).

else if (PlatformDetection.ICUVersion >= new Version(72, 1, 0, 4))

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[tarekgh]

CC @kunalspathak

[kunalspathak]

/azp run runtime-coreclr libraries-jitstress

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