[WIP] Support file_scoped namespace declarations when generating code

[Copilot]

• Reset branch to latest main (18eec74)
• Re-apply file-scoped namespace changes
  • Create CSharpCodeGenerationConfiguration class
  • Update IEditorConfigOptionsProvider interface with GetEditorConfigOptionsByPath
  • Update EditorConfigOptionsProvider implementation
  • Update DefineStepsCommand with GenerateStepDefinitionClass method
  • Update StubEditorConfigOptionsProvider for tests
  • Add unit tests with approval test data
  • Update CHANGELOG.md
• Fix build failures
  • Fix DefineStepsCommand constructor call in ProjectSystemSteps.cs
  • Add missing usings to DefineStepsCommand
• Verify tests pass locally
• Trigger CI to verify all tests pass

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