MA0110: Derive generated regex names from field/variable context

[Copilot]

MA0110's code fix always suggested "MyRegex" regardless of where the Regex instantiation occurred. This leads to poor code clarity and naming conflicts.

Changes

Fixer (UseRegexSourceGeneratorFixer.cs)

• Walk operation tree via operation.Ancestors() to detect IFieldInitializerOperation or IVariableDeclaratorOperation
• For fields (length > 1): use field name as-is
• For variables (length > 1): convert to PascalCase
• Compute suggested name directly in the fixer
• Fall back to "MyRegex" for single-char names or no context
• Existing uniqueness checking handles conflicts

Analyzer (UseRegexSourceGeneratorAnalyzer.cs)

• No changes - remains focused on detection only

Example

Before:

class Sample {
    private static readonly Regex EmailPattern = new Regex(@"\w+@\w+");
    // Code fix suggested: MyRegex() or MyRegex_()
}

After:

class Sample {
    private static readonly Regex EmailPattern = EmailPattern_();
    // Code fix now suggests: EmailPattern() (with _ if needed for uniqueness)
    
    [GeneratedRegex(@"\w+@\w+")]
    private static partial Regex EmailPattern_();
}

Variables follow same pattern with PascalCase conversion:

void Method() {
    Regex emailPattern = new Regex(@"\w+@\w+");
    // Suggests: EmailPattern()
}

Limitations

Does not yet remove original field/variable declarations or replace all usages—would require symbol finding and reference replacement across the document.

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