fix(@angular-devkit/build-angular): resolve i18n outFile with normalized format

IF someone uses the `extract-i18n` with the deprecated `--i18n-format` option,
then `options.format` is undefined and the `outFile` defaults to `messages.xlf`,
whereas the content will be using the proper format.

(cherry picked from commit 748c1f8)

Author: cexbrayat

packages/angular_devkit/build_angular/src/extract-i18n/index.ts

@@ -147,7 +147,7 @@ export async function execute(
   const format = normalizeFormatOption(options);
 
   // We need to determine the outFile name so that AngularCompiler can retrieve it.
-  let outFile = options.outFile || getI18nOutfile(options.format);
+  let outFile = options.outFile || getI18nOutfile(format);
   if (options.outputPath) {
     // AngularCompilerPlugin doesn't support genDir so we have to adjust outFile instead.
     outFile = path.join(options.outputPath, outFile);