feat(common): add a titlecase pipe (#13324)

closes #11436

tools/public_api_guard/common/index.d.ts

@@ -223,6 +223,11 @@ export declare class SlicePipe implements PipeTransform {
     transform(value: any, start: number, end?: number): any;
 }
 
+/** @stable */
+export declare class TitleCasePipe implements PipeTransform {
+    transform(value: string): string;
+}
+
 /** @stable */
 export declare class UpperCasePipe implements PipeTransform {
     transform(value: string): string;