Tests for Open-AI Plugin

Problem: Currently we have no tests for the OpenAI-Plugin

Solution: Adding tests:

• One test to test the general translation of a smaller task with OpenAI
• One test to test the termtagger integration when translating (test-data oversized segment: nextcloud/Developer/test-data/basic import/3-segments-with-tags-oversized-de-en.xliff
• One test to test the system-message & example management (create sys-messages creation, test example creation)
• If possible: One test to the model training functionality

Challenges

• We needs an OpenAI-Account to test with. MOC-data tests make no sense since we also must be prepared for API-changes
• OpenAI answers often in an unpredictable way. Therefore we may must check intermediate-results (which is currently not possible via API)