extensions/typescript-language-features/src/utils/configuration.ts/BaseServiceConfigurationProvider/readUseSyntaxServer
class BaseServiceConfigurationProvider:	protected readUseSyntaxServer(configuration: vscode.WorkspaceConfiguration): SyntaxServerConfiguration {
		const value = configuration.get<string>('typescript.tsserver.useSyntaxServer');
		switch (value) {
			case 'never': return SyntaxServerConfiguration.Never;
			case 'always': return SyntaxServerConfiguration.Always;
			case 'auto': return SyntaxServerConfiguration.Auto;
		}

		// Fallback to deprecated setting
		const deprecatedValue = configuration.get<boolean | string>('typescript.tsserver.useSeparateSyntaxServer', true);
		if (deprecatedValue === 'forAllRequests') { // Undocumented setting
			return SyntaxServerConfiguration.Always;
		}
		if (deprecatedValue === true) {
			return SyntaxServerConfiguration.Auto;
		}
		return SyntaxServerConfiguration.Never;
	}