[FEATURE] Avatar link with tooltip

Implement a BitAvatar component inspired by the design and UX of the Bootstrap Italia Avatar component with support of Tooltips.

### Requirements:
Describe the list of requirements this feature needs:
- Extend the BitAvatar component adding support for ([docs](https://italia.github.io/bootstrap-italia/docs/componenti/avatar/#avatar-link-con-tooltip)).
- Expose properties for tooltip content.
- Expose parameters for ARIA/accessibility attributes.
- Ensure full accessibility including keyboard navigation, ARIA attributes, and screen reader support.
- Responsive design and mobile-friendly behavior.
- Requires #46 , #9

### Acceptance Criteria:
- The component renders valid Bootstrap Italia avatar markup.
- All documented variants and styles are supported via parameters.
- The component is unit tested for all major styles.
- Usage examples are provided in the documentation or a sample page.

### References
- Bootstrap Italia - Avatars with tooltip documentation ([docs](https://italia.github.io/bootstrap-italia/docs/componenti/avatar/#avatar-link-con-tooltip))