feat: add Mockaco module

[raffreitas]

What does this PR do?

This PR introduces a new Mockaco module, providing HTTP mock server capabilities for integration testing.

Why is it important?

Mockaco (official project) is a popular HTTP mock server that's widely used in .NET integration testing scenarios. This module fills a gap in the Testcontainers.NET ecosystem by providing:

1. Mock verification capabilities: Developers can verify that their applications made the expected HTTP calls during tests
2. Integration testing support: Enables testing of HTTP client behavior without relying on external services
3. Test isolation: Each test can have its own mock server instance with independent verification data
4. Developer productivity: Simplifies setup and teardown of HTTP mocks in containerized test environments

The verification functionality is particularly valuable for testing:

• API integrations
• HTTP client implementations
• Service-to-service communication
• Request/response validation in microservices

Template-based configuration: Mockaco uses JSON template files to define mock endpoints, providing flexibility and easy maintenance of mock definitions.

How to test this PR

1. Build the solution:

   .\build.ps1

2. Run specific Mockaco tests:

   dotnet test tests/Testcontainers.Mockaco.Tests/ -v normal

3. Create a template file (required for Mockaco to work):

    // ./templates/ping-pong.json
    {
      "request": {
        "method": "GET",
        "route": "ping"
      },
      "response": {
        "status": "OK",
        "body": {
          "response": "pong"
        }
      }
    }

4. Test verification functionality:

   // Example usage from the test suite
   var container = new MockacoBuilder()
       .WithTemplatesPath("./templates")
       .Build();
   await container.StartAsync();
   
   // Make HTTP calls to the mock server
   var httpClient = new HttpClient();
   await httpClient.GetAsync(container.GetBaseAddress() + "/ping");
   
   // Verify the calls were made
   var verification = await container.GetVerifyAsync("/ping");
   Assert.NotNull(verification);
   Assert.Equal("/ping", verification.Route);
   Assert.Contains("pong", verification.Body)

5. Check documentation:
   Review docs/modules/mockaco.md for usage examples and template setup
   Verify examples work with the implementation

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