Add Testcontainers support for more integration tests

[poikilotherm]

As a result of #5068, #6783, #6694 and many more cases and ideas, I would like to propose adding support for https://www.testcontainers.org.

Small PR forthcoming, adding the necessary bits in pom.xml to enable JUnit Tests using the framework plus adding a tc profile to keep things out of the way for devs not using the technology.

Will also feature some doc changes on how to use this. Needs some refactoring of the testing guide.

This is related to @donsizemore efforts in IQSS/dataverse-ansible#164. IMHO we should use more JUnit to execute and navigate through tests, being the current standard in the codebase.