java-design-patterns Added Microservices UI Client side composition #2698

What problem does this PR solve?

This PR implements the Client-Side UI Composition pattern, as described in issue #2698. The pattern allows the user interface to be composed on the client-side, using micro frontends and an API Gateway, ensuring a modular and flexible UI.

Close #2698

Key Elements of the Implementation:

Micro Frontends: Independent frontend modules that can be developed, tested, and deployed separately.
API Gateway: A routing mechanism that directs client requests to the appropriate microservices.
Client-Side Integration Layer: A dynamic layer that integrates the UI components into a cohesive user experience.
Asynchronous Data Fetching: Ensures non-blocking data loading for each frontend component, enhancing user experience.

Acceptance Criteria:

Micro frontends are developed as independent modules.
An API Gateway is implemented to route client requests securely and efficiently.
The client-side integration layer dynamically assembles the UI components.
Each frontend component fetches its data asynchronously using non-blocking mechanisms.

Testing and Documentation:

Comprehensive tests are included to ensure the integrity of the integrated UI components.
Detailed documentation is provided on setting up and using the Client-Side UI Composition pattern.