Crash in `RemoveUnnecessarySuppressions` caused by multi-variable declaration

[John-Leitch]

Crash in RemoveUnnecessarySuppressions caused by multi-variable declaration

Version Used:

Encountered in VS 2022 17.14.0 Preview 7.0. Also repro'ed in main.

Steps to Reproduce:

Attempt to remove the unnecessary suppression in the following declaration:

namespace Test;

public static class C
{
    [System.Diagnostics.CodeAnalysis.SuppressMessage("Naming", "CA1720:Identifier contains type name", Justification = "<Pending>")]
    public static event EventHandler Foo, Bar;
}

Expected Behavior:
Removal of unncessary suppression attribute.

Actual Behavior:
Crash:

Stack Trace:

StreamJsonRpc.RemoteInvocationException: An item with the same key has already been added. Key: System.Diagnostics.CodeAnalysis.SuppressMessage("Naming", "CA1720:Identifier contains type name", Justification = "<Pending>")
   at StreamJsonRpc.JsonRpc.<InvokeCoreAsync>d__156`1.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.CodeAnalysis.Remote.BrokeredServiceConnection`1.<TryInvokeAsync>d__18`1.MoveNext()
RPC server exception:
System.ArgumentException: An item with the same key has already been added. Key: System.Diagnostics.CodeAnalysis.SuppressMessage("Naming", "CA1720:Identifier contains type name", Justification = "<Pending>")
      at System.Collections.Generic.Dictionary`2.TryInsert(TKey key, TValue value, InsertionBehavior behavior)
      at System.Collections.Generic.Dictionary`2.Add(TKey key, TValue value)
      at Microsoft.CodeAnalysis.RemoveUnnecessarySuppressions.AbstractRemoveUnnecessaryInlineSuppressionsDiagnosticAnalyzer.ProcessSuppressMessageAttributesAsync(SyntaxNode root, SemanticModel semanticModel, Nullable`1 span, PooledDictionary`2 idToSuppressMessageAttributesMap, PooledDictionary`2 suppressMessageAttributesToIsUsedMap, ImmutableArray`1 userIdExclusions, ImmutableArray`1 userCategoryExclusions, CancellationToken cancellationToken)
      at Microsoft.CodeAnalysis.RemoveUnnecessarySuppressions.AbstractRemoveUnnecessaryInlineSuppressionsDiagnosticAnalyzer.AnalyzeAsync(SemanticModel semanticModel, Nullable`1 span, CompilationWithAnalyzers compilationWithAnalyzers, Func`2 getSupportedDiagnostics, Action`1 reportDiagnostic, CancellationToken cancellationToken)
      at Microsoft.CodeAnalysis.Diagnostics.Extensions.<GetPragmaSuppressionAnalyzerDiagnosticsAsync>g__AnalyzeDocumentAsync|12_0(CompilationWithAnalyzers hostCompilationWithAnalyzers, DiagnosticAnalyzerInfoCache analyzerInfoCache, IPragmaSuppressionsAnalyzer suppressionAnalyzer, Document document, Nullable`1 span, Action`1 reportDiagnostic, CancellationToken cancellationToken)
      at Microsoft.CodeAnalysis.Diagnostics.Extensions.GetPragmaSuppressionAnalyzerDiagnosticsAsync(CompilationWithAnalyzersPair compilationWithAnalyzers, DocumentAnalysisScope documentAnalysisScope, Project project, DiagnosticAnalyzerInfoCache analyzerInfoCache, CancellationToken cancellationToken)
      at Microsoft.CodeAnalysis.Diagnostics.Extensions.GetAnalysisResultAsync(CompilationWithAnalyzersPair compilationWithAnalyzers, DocumentAnalysisScope documentAnalysisScope, Project project, DiagnosticAnalyzerInfoCache analyzerInfoCache, CancellationToken cancellationToken)
      at Microsoft.CodeAnalysis.Remote.Diagnostics.DiagnosticComputer.AnalyzeAsync(CompilationWithAnalyzersPair compilationWithAnalyzers, BidirectionalMap`2 analyzerToIdMap, ImmutableArray`1 projectAnalyzers, ImmutableArray`1 hostAnalyzers, SkippedHostAnalyzersInfo skippedAnalyzersInfo, Boolean logPerformanceInfo, Boolean getTelemetryInfo, CancellationToken cancellationToken)
      at Microsoft.CodeAnalysis.Remote.Diagnostics.DiagnosticComputer.GetDiagnosticsAsync(ImmutableArray`1 projectAnalyzerIds, ImmutableArray`1 hostAnalyzerIds, Boolean logPerformanceInfo, Boolean getTelemetryInfo, CancellationToken cancellationToken)
      at Microsoft.CodeAnalysis.Remote.Diagnostics.DiagnosticComputer.GetHighPriorityDiagnosticsAsync(ImmutableArray`1 projectAnalyzerIds, ImmutableArray`1 hostAnalyzerIds, Boolean logPerformanceInfo, Boolean getTelemetryInfo, CancellationToken cancellationToken)
      at Microsoft.CodeAnalysis.Remote.RemoteDiagnosticAnalyzerService.<>c__DisplayClass3_0.<<CalculateDiagnosticsAsync>b__0>d.MoveNext()
   --- End of stack trace from previous location ---
      at Microsoft.CodeAnalysis.Remote.RemoteWorkspace.<>c__DisplayClass7_0`1.<<RunWithSolutionAsync>g__ProcessSolutionAsync|1>d.MoveNext()
   --- End of stack trace from previous location ---
      at Microsoft.CodeAnalysis.Remote.RemoteWorkspace.RunWithSolutionAsync[T](AssetProvider assetProvider, Checksum solutionChecksum, Boolean updatePrimaryBranch, Func`2 implementation, CancellationToken cancellationToken)
      at Microsoft.CodeAnalysis.Remote.RemoteWorkspace.RunWithSolutionAsync[T](AssetProvider assetProvider, Checksum solutionChecksum, Boolean updatePrimaryBranch, Func`2 implementation, CancellationToken cancellationToken)
      at Microsoft.CodeAnalysis.Remote.BrokeredServiceBase.RunWithSolutionAsync[T](Checksum solutionChecksum, Func`2 implementation, CancellationToken cancellationToken)
      at Microsoft.CodeAnalysis.Remote.RemoteDiagnosticAnalyzerService.CalculateDiagnosticsAsync(Checksum solutionChecksum, DiagnosticArguments arguments, CancellationToken cancellationToken)