Fix macOS CI failure by aligning formatting fallback with Eclipse editor preferences

[Copilot]

build (macos-latest) was failing due to FormatOptionProviderTests expecting editor-derived indentation defaults, while production fallback logic returned hardcoded values for unknown/no-extension files. This change makes fallback behavior preference-driven and updates tests to assert the same source of truth.

• Problem

  • FormatOptionProvider defaulted to hardcoded space + tabSize=4 when no language-specific formatter was available, diverging from Eclipse editor preference behavior on macOS.

• Production change

  • In FormatOptionProvider, unknown language and no-extension paths now resolve indentation from org.eclipse.ui.editors preferences:
    • spacesForTabs
    • tabWidth
  • Retains hardcoded defaults only as an error fallback, with exception logging for diagnostics.

• Test alignment

  • FormatOptionProviderTests now computes expected values from the same Eclipse preference service instead of asserting hardcoded defaults for unknown/no-extension cases.

IPreferencesService service = Platform.getPreferencesService();
boolean useSpaces = service.getBoolean("org.eclipse.ui.editors", "spacesForTabs", true, null);
int tabSize = service.getInt("org.eclipse.ui.editors", "tabWidth", 4, null);
return new FormattingOptions(tabSize, useSpaces);