separate viewsets into files

[Floris272]

producttypes/views is becoming a bit too large so it would be a good idea to split so that each viewset has it's own file. This file contains the viewset with drf schema annotation and action and the used FilterSet class

• Some api test files are also too large and can be split into tests for crud, actions and filters

• Admin tests could also have their own folder.

• define request & response examples for all methods

  • add response and request sample to every viewset
  • add examples to every method of extend_schema_view