The `Product` namespace segment in the domain model namespace
`TTN\Tea\Domain\Model` currently serves no purpose and only adds
confusion. So let's simplify the extension structure accordingly.
(I intended to use this to demonstrate DDD contexts, but never
built enough models in the Tea extension for this to actually
make sense.)
Fixes#1008
That way the extension serves as an example on how to use the TYPO3
internal requests provided by the TYPO3 testing framework.
Those can be used as integration tests.
They are also often easier to set up on existing projects and allow to
refactor the code base, compared to functional and unit tests.
Resolves: #859
