feat(common): export NgLocaleLocalization (#13367)

Closes #11921

modules/@angular/common/src/common.ts

@@ -12,7 +12,7 @@
  * Entry point for all public APIs of the common package.
  */
 export * from './location/index';
-export {NgLocalization} from './localization';
+export {NgLocaleLocalization, NgLocalization} from './localization';
 export {CommonModule} from './common_module';
 export {NgClass, NgFor, NgIf, NgPlural, NgPluralCase, NgStyle, NgSwitch, NgSwitchCase, NgSwitchDefault, NgTemplateOutlet} from './directives/index';
 export {AsyncPipe, DatePipe, I18nPluralPipe, I18nSelectPipe, JsonPipe, LowerCasePipe, CurrencyPipe, DecimalPipe, PercentPipe, SlicePipe, UpperCasePipe, TitleCasePipe} from './pipes/index';

modules/@angular/common/src/localization.ts

@@ -49,10 +49,10 @@ export function getPluralCategory(
  */
 @Injectable()
 export class NgLocaleLocalization extends NgLocalization {
-  constructor(@Inject(LOCALE_ID) private _locale: string) { super(); }
+  constructor(@Inject(LOCALE_ID) protected locale: string) { super(); }
 
   getPluralCategory(value: any): string {
-    const plural = getPluralCase(this._locale, value);
+    const plural = getPluralCase(this.locale, value);
 
     switch (plural) {
       case Plural.Zero:

tools/public_api_guard/common/index.d.ts

@@ -135,6 +135,13 @@ export declare class NgIf {
     constructor(_viewContainer: ViewContainerRef, templateRef: TemplateRef<NgIfContext>);
 }
 
+/** @experimental */
+export declare class NgLocaleLocalization extends NgLocalization {
+    protected locale: string;
+    constructor(locale: string);
+    getPluralCategory(value: any): string;
+}
+
 /** @experimental */
 export declare abstract class NgLocalization {
     abstract getPluralCategory(value: any): string;