feat(modal): add confirm and confirm delete modals with tests

- Implemented ConfirmModalComponent and ConfirmDeleteModalComponent for confirmation dialogs.
- Added modal service methods to open confirm and confirm delete modals.
- Created corresponding HTML and SCSS files for both modal components.
- Updated ReutilizablesTestPageComponent to utilize new modals.
- Enhanced modal service tests to cover new functionality.
- Refactored existing tests to accommodate changes in modal behavior and structure.

src/app/shared/components/modal-shell/modal-shell.component.scss

@@ -49,16 +49,26 @@
 }
 
 .modal-shell__header {
+  position: relative;
+  justify-content: center;
   align-items: flex-start;
   padding: 1.25rem 1.25rem 0.75rem;
 }
 
 .modal-shell__title {
   margin: 0;
+  width: 100%;
   font-size: clamp(1.15rem, 1rem + 0.4vw, 1.5rem);
   font-weight: 700;
   line-height: 1.15;
   color: #202020;
+  text-align: center;
+}
+
+.modal-shell__header .btn-close {
+  position: absolute;
+  top: 1.25rem;
+  right: 1.25rem;
 }
 
 .modal-shell__body {