Provide JUnit5 extensions in addition to JUnit4 rules

https://github.com/adobe/aem-testing-clients/wiki/Best-practices#junit-rules should be accompanied with according extensions for JUnit 5 (https://junit.org/junit5/docs/current/user-guide/#extensions)

Start with the linked wiki section describing the existing JUnit 4 rules, then read the linked JUnit 5 extensions guide to identify the corresponding extension model. Done means providing JUnit 5 extensions that accompany the documented rules, with compatibility and scope confirmed against the project's existing testing tools.

Written by the indexing model from the issue text.