MA0007: Support multiline pattern-matching expressions

[Copilot]

MA0007 was not detecting missing trailing commas in multiline is { } pattern-matching expressions.

var res = contract is
{
    One: false,
    Two: false  // Missing comma not detected
};

Changes

• Added HandleRecursivePattern handler for SyntaxKind.RecursivePattern nodes
• Extracts PropertyPatternClause.Subpatterns and passes to existing HandleSeparatedList logic
• Added tests covering multiline with/without trailing comma and single-line patterns

The fix reuses the existing separated list handling, treating property pattern clauses like other multiline constructs (object initializers, switch expressions, etc.).

Original prompt

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This section details on the original issue you should resolve

<issue_title>MA0007 is not triggered in multiline pattern-matching expressions</issue_title>
<issue_description>### Version of the Meziantou.Analyzer NuGet package

2.0.286

Rule Identifier

MA0007

Target Framework

net8.0

C# Language version

C# 12

Description

Resharper's analyzer shows that a comma should be added after the last clause in a multiline is { } expression, but Meziantou Analyzers don't, so it can't be enforced during build.

Reproduction Steps

Minimal code:

var res = contract is
{
    One: false,
    Two: false
};

Other information

No response</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes MA0007 is not triggered in multiline pattern-matching expressions #996

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