Honor scoped .editorconfig settings in Roslyn formatter requests

[Copilot]

Roslyn-formatting requests were ignoring document-scoped configuration, so .editorconfig values such as indent_size and csharp_new_line_before_open_brace were not applied in newer extension versions. This updates the LSP configuration path to return per-document formatting settings instead of falling back to global defaults.

• Root cause

  • workspace/configuration requests with scopeUri were treated as unsupported in the Roslyn LSP middleware.
  • That caused formatter option lookups to return null for document-scoped settings, bypassing .editorconfig-resolved values.

• Change

  • Update configurationMiddleware to resolve settings with the request scope:
    • use { languageId: 'csharp', uri } when scopeUri is present
    • continue to use C# language-scoped defaults when no URI is provided
  • Update universalEditorConfigProvider to read fallback VS Code formatting settings from the same scope instead of an unscoped configuration object.

• Regression coverage

  • Add unit coverage for scoped configuration reads and scoped fallback resolution.
  • Strengthen the existing formatting integration asset/test to validate both:
    • brace placement from .editorconfig
    • indentation width from .editorconfig

• Example

  [*.cs]
  indent_size = 2
  indent_style = space
  csharp_new_line_before_open_brace = none

  With this change, formatting requests for that document now resolve options from the document scope, so output follows the file’s .editorconfig instead of extension/global defaults.