Sergey Karpov

IDE freezes when I invoked the Rename refactoring. I saw IRen in thread dumps and disabling the IRen plugin solves this performance issue. I attached threadDumps. [threadDumps-freeze-20230409-010926-PY-231.8109.197-106sec.zip](https://github.com/JetBrains-Research/IRen/files/11198795/threadDumps-freeze-20230409-010926-PY-231.8109.197-106sec.zip)

Add capabilities integration tests and fix AbstractOpenAILLMClient for plain text

1

## Tests 1. Positive - check the model actually has specified capabilities by trying to use them. 2. Negative - check that trying to use a capability that a model...