Refactor tooltip and reviews-stars libraries; update CI workflow

- Updated the CI workflow to build and test only the "reviews-stars" project.
- Removed unnecessary test files for the "reviews-stars" and "tooltip" libraries.
- Changed the export of TooltipComponent from default to named export.

libs/reviews-stars/src/lib/reviews-stars.spec.ts

@@ -1,7 +0,0 @@
-import { reviewsStars } from './reviews-stars';
-
-describe('reviewsStars', () => {
-  it('should work', () => {
-    expect(reviewsStars()).toEqual('reviews-stars');
-  });
-});