Banner Service Integration into Microservice Demo + Banner Call from Frontend

[MaximilianSchreff]

This PR introduces the integration of the Banner Service into the Microservice Demo project. It sets up the gRPC client for the Banner Service and implements a call to fetch banner data during the loading of the homepage in the frontend.

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Key Changes:

1. Banner Service Client Integration:

   • Added a gRPC client for the Banner Service using the generated protobuf and gRPC stubs (bannerpb).
   • Configured the client initialization in main.go, fetching the service address (BANNER_SERVICE_ADDR) from environment variables.

2. gRPC Call to GetCurrentBanner:

   • Updated homeHandler in handlers.go to call the GetCurrentBanner method of the Banner Service.
   • Hardcoded Location parameter for the banner request as "DE" for now.

3. Environment Configuration:

   • Ensured the BANNER_SERVICE_ADDR is injected through environment variables.
   • Verified compatibility with Skaffold and Kubernetes deployment setups.

4. Data Injection:

   • The banner data (Title, Description, Image, ImageFormat) is retrieved from the Banner Service and prepared for injection into the template rendering pipeline.

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Next Steps:

• Inject data: banner data (Title, Description, Image, ImageFormat) is retrieved from the Banner Service and prepared for injection into the template rendering pipeline.
• Update the HTML templates to display the banner dynamically using the injected data.
• Add unit tests for the banner integration (mocking the gRPC client).

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Testing:

• Verified the gRPC connection to the Banner Service in a local development environment.

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