Test methods with out or ref parameters are not properly supported by the test framework. This PR adds a new informational analyzer with automatic code fix and runtime warning to help users identify and migrate away from this pattern before support is dropped in a future major version.

Example code that triggers the warning:

[TestMethod]
[DataRow("Hello", "World")]
public void TestMethod1(out string s, ref string s2)  // ℹ️ MSTEST0060 info diagnostic
{
    s = "";
}

Changes Made

New Analyzer (MSTEST0060)

• Created: AvoidOutRefTestMethodParametersAnalyzer as a separate analyzer
• Severity: Info (informational suggestion, not warning)
• Category: Usage
• Message: "Test method '{0}' has 'out' or 'ref' parameters for which support will be dropped in a future major version"
• Description: "'out' and 'ref' parameters add no value in test methods and they can safely be replaced by normal parameters."
• Supports: All attributes inheriting from [TestMethod] (e.g., [DataTestMethod])

Code Fix

• Created: AvoidOutRefTestMethodParametersFixer
• Action: Automatically removes out and ref modifiers from test method parameters
• Title: "Remove 'out' and 'ref' modifiers"
• Implementation: Simplified to directly find the method declaration using FindNode and always apply changes (no unnecessary checks)
• Supports: Batch fixing via FixAllProvider

Runtime Warning

• Modified: TestMethodValidator.IsValidTestMethod to detect out/ref parameters during test discovery/validation
• Behavior: Method returns true (non-blocking) but adds warning to the warnings collection
• Message: Uses Resource.UTA_OutRefParametersNotSupported for consistency across compile-time and runtime
• Optimization: Checks parameters.Length > 0 before LINQ enumeration to avoid unnecessary overhead

Localization

• Added 3 resource strings in analyzer Resources.resx
• Added 1 resource string in code fix CodeFixResources.resx
• Added 1 resource string in runtime Resource.resx
• Note: xlf files are auto-generated during build and have been updated with correct indentation

Tests

• Updated AvoidOutRefTestMethodParametersAnalyzerTests.cs with code fix verification
• Added test for [DataTestMethod] attribute to verify inheritance detection
• 6 comprehensive test cases covering: out parameters, ref parameters, both together, normal parameters, non-test methods, and inherited test method attributes
• Tests verify both diagnostic detection and code fix application

Migration Path

This approach provides a gradual, non-breaking migration path with automatic fix capability:

1. Now: Users receive informational warnings at compile-time and during test discovery, with one-click code fix available
2. Later: Can upgrade to stricter enforcement (blocking) in a future major version

Not a breaking change: Existing tests with out/ref parameters continue to run, but users are warned about the pattern during validation and can automatically fix it.

• Fixes Disallow test methods with out/ref parameters #7058

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