Added conversational history parameter for openai

[selectorseb]

Description

Added a parameter to add conversational history supported by openai

which is the ChatML User/Assisant model.
Example:
[{"role": "user", "content": messge1},
{"role": "assistant", "content": messge2}] is an example of a conversation held by the user and reponse by llm, wich can be appended to the api request to openai

Corresponding documentation PR

Types of change

Checklist

• I confirm that I have the right to submit this contribution under the project's MIT license.
• I ran all tests in tests and usage_examples/tests, and all new and existing tests passed. This includes
  • all external tests (i. e. pytest ran with --external)
  • all tests requiring a GPU (i. e. pytest ran with --gpu)
• My changes don't require a change to the documentation, or if they do, I've added all required information.