Add JUnit 5 support test coverage and documentation

[oleg-nenashev]

Summary

The code should work for JUnit 5, but it has not been tested yet. It would be nice to have a few tests and an example in the documentation

References

No response

[bitxon]

What is the suggested approach to manage junit4 and junit5 tests?

Option 1
Keep junit4 and junit5 classes close to each other by copying existing tests and adjust for Junit5. So we will have structure like that:

src
├── main
│   └── ...
├── test
│   ├── java
│   │   └── org.wiremock.integrations.testcontainers
│   │       ├── WireMockContainerExtensionJunit4Test
│   │       ├── WireMockContainerExtensionJunit5Test
│   │       ├── WireMockContainerJunit4Test
│   │       └── WireMockContainerJunit5Test
│   └── resources
│       ├── logback-test.xml
│       └── org.wiremock.integrations.testcontainers
│           ├── WireMockContainerExtensionJunit4Test
│           ├── WireMockContainerExtensionJunit5Test
│           ├── WireMockContainerJunit4Test
│           └── WireMockContainerJunit5Test
└── ...

Option 2
Add separate test source folder using build-helper-maven-plugin so we will have following structure

src
├── main
│   └── ...
├── test-junit4
│   ├── java
│   │   └── org.wiremock.integrations.testcontainers
│   │       ├── WireMockContainerExtensionJunit4Test
│   │       └──  WireMockContainerJunit4Test
│   └── resources
│       ├── logback-test.xml
│       └── org.wiremock.integrations.testcontainers
│           ├── WireMockContainerExtensionJunit4Test
│           └── WireMockContainerJunit4Test
├── test-junit5
│   ├── java
│   │   └── org.wiremock.integrations.testcontainers
│   │       ├── WireMockContainerExtensionJunit45Test
│   │       └──  WireMockContainerJunit5Test
│   └── resources
│       ├── logback-test.xml
│       └── org.wiremock.integrations.testcontainers
│           ├── WireMockContainerExtensionJunit5Test
│           └── WireMockContainerJunit5Test
└── ...

[oleg-nenashev]

@bitxon I would keep the first approach for now. If we have too many tests in the future, which would be a good problem to have, we could refactor it. I doubt there will be too many test files, and not all tests will require JUnit 4 and 5 coverage

FTR there is a patch from @kapishmalik in #16