fix(compiler): compile .ngfactory.ts files even if nobody references them. (#16899)

This is especially important for library authors, as they will
not reference the .ngfactory.ts files.

Fixes #16741

packages/compiler-cli/src/extract_i18n.ts

@@ -21,7 +21,7 @@ import {Extractor} from './extractor';
 
 function extract(
     ngOptions: tsc.AngularCompilerOptions, cliOptions: tsc.I18nExtractionCliOptions,
-    program: ts.Program, host: ts.CompilerHost): Promise<void> {
+    program: ts.Program, host: ts.CompilerHost) {
   return Extractor.create(ngOptions, program, host, cliOptions.locale)
       .extract(cliOptions.i18nFormat !, cliOptions.outFile);
 }