The ParseCoordinator could use some unit tests

[MDoerner]

Currently, we have no unit tests for the ParseCoordinator. This is primarily a consequence of it doing way too much in the past.

Since it has been refactored to only coordinate the parsing process it should be possible to write unit tests for it, i.e. tests verifying that it passes the correct modules to the different components. In particular, we could test that the correct calls are made for the cache invalidation.

Unfortunately, this will be a huge endeavor because the behaviour is complicated and there are lots of parts to mock. (Fortunately, most dependencies are hidden behind two service interfaces.)