[Feature Request]: Allow user to add extra "type of test" in pipeline unit test

### What would you like to happen?

Currently, only 2 types of tests can be added to the pipeline unit tests.

It would be an excellent extra to be able to add custom types and populate the dropdown based on all types found inside the project.

The same would then apply to the execute unit tests transform, it should list all types found inside the project

### Issue Priority

Priority: 3

### Issue Component

Component: Transforms

Start by locating the pipeline unit test configuration and the execute unit tests transform, then inspect how their current two test types populate the dropdown. Confirm how available types can be found across the project. Done means both locations discover and list project-defined types, while retaining the existing test behavior.

Written by the indexing model from the issue text.