feat(compiler-cli): add an outFile option to ng-xi18n

Fixes #11416
Closes #14508
Closes #14657

modules/@angular/compiler-cli/integrationtest/test/i18n_spec.ts

@@ -68,7 +68,7 @@ describe('template i18n extraction output', () => {
   const genDir = 'out';
 
   it('should extract i18n messages as xmb', () => {
-    const xmbOutput = path.join(outDir, 'messages.xmb');
+    const xmbOutput = path.join(outDir, 'custom_file.xmb');
     expect(fs.existsSync(xmbOutput)).toBeTruthy();
     const xmb = fs.readFileSync(xmbOutput, {encoding: 'utf-8'});
     expect(xmb).toEqual(EXPECTED_XMB);

modules/@angular/compiler-cli/integrationtest/test/test_ngtools_api.ts

@@ -132,6 +132,7 @@ function i18nTest() {
         angularCompilerOptions: config.ngOptions,
         i18nFormat: 'xlf',
         locale: null,
+        outFile: null,
         readResource: (fileName: string) => {
           readResources.push(fileName);
           return hostContext.readResource(fileName);