Add measurement options dialog

[yangfei]

Summary

• Add MeasurementOptions with current default result columns preserved.
• Add Analyze > Set Measurements... with checkboxes for Area, Mean, Min, Max, and StdDev.
• Rebuild the results table for future measurements based on selected options.
• Add tests for option defaults, limited columns, and Form1 measurement output.

Verification

• dotnet build ImageJCsharp.sln
• dotnet test tests/ImageJCsharp.Core.Tests/ImageJCsharp.Core.Tests.csproj
• dotnet test tests/ImageJCsharp.App.Tests/ImageJCsharp.App.Tests.csproj

Closes #16