Add Testcontainers-based Integration Testing

[ajeetraina]

This PR adds a comprehensive testing framework using Testcontainers for the GenAI application.

Features Added

1. Basic Test Framework:

   • Setup for testing the GenAI application
   • Test helpers for making API requests
   • Simplified test environment setup

2. Testcontainers Integration:

   • Placeholder for container-based testing
   • Structure for testing with isolated containers
   • Simplified implementation for initial testing

3. Test Categories:

   • API Integration Tests: Verifies endpoints and basic functionality
   • LLM Quality Tests: Basic structure for testing response quality
   • Performance Tests: Structure for testing response times
   • Multi-turn Conversation Tests: Structure for testing context maintenance

4. Convenience Features:

   • Skip tests in short mode
   • Makefile for running different test scenarios
   • Documentation for using the test framework

Current Implementation

This is a simplified implementation to get the tests running. The full Testcontainers functionality will be implemented incrementally:

1. First phase (this PR): Get the tests to compile and run against a local environment
2. Second phase: Implement actual container creation with Testcontainers
3. Third phase: Add more sophisticated test cases and validation

How to Run

cd tests
go test -v ./integration            # Run all tests
go test -v ./integration -short     # Run only short tests

See the TESTCONTAINERS.md file for more details and options.